120
\$\begingroup\$

The Fibonacci sequence is a sequence of numbers, where every number in the sequence is the sum of the two numbers preceding it. The first two numbers in the sequence are both 1.

Here are the first few terms

1 1 2 3 5 8 13 21 34 55 89 ...

Write the shortest code that either:

  • Generates the Fibonacci sequence without end.

  • Given n calculates the nth term of the sequence. (Either 1 or zero indexed)

You may use standard forms of input and output.

(I gave both options in case one is easier to do in your chosen language than the other.)


For the function that takes an n, a reasonably large return value (the largest Fibonacci number that fits your computer's normal word size, at a minimum) has to be supported.


Leaderboard

/* Configuration */

var QUESTION_ID = 85; // Obtain this from the url
// It will be like https://XYZ.stackexchange.com/questions/QUESTION_ID/... on any question page
var ANSWER_FILTER = "!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe";
var COMMENT_FILTER = "!)Q2B_A2kjfAiU78X(md6BoYk";
var OVERRIDE_USER = 3; // This should be the user ID of the challenge author.

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}

getAnswers();

var SCORE_REG = /<h\d>\s*([^\n,<]*(?:<(?:[^\n>]*>[^\n<]*<\/[^\n>]*>)[^\n,<]*)*),.*?(\d+)(?=[^\n\d<>]*(?:<(?:s>[^\n<>]*<\/s>|[^\n<>]+>)[^\n\d<>]*)*<\/h\d>)/;

var OVERRIDE_REG = /^Override\s*header:\s*/i;

function getAuthorName(a) {
  return a.owner.display_name;
}

function process() {
  var valid = [];
  
  answers.forEach(function(a) {
    var body = a.body;
    a.comments.forEach(function(c) {
      if(OVERRIDE_REG.test(c.body))
        body = '<h1>' + c.body.replace(OVERRIDE_REG, '') + '</h1>';
    });
    
    var match = body.match(SCORE_REG);
    if (match)
      valid.push({
        user: getAuthorName(a),
        size: +match[2],
        language: match[1],
        link: a.share_link,
      });
    else console.log(body);
  });
  
  valid.sort(function (a, b) {
    var aB = a.size,
        bB = b.size;
    return aB - bB
  });

  var languages = {};
  var place = 1;
  var lastSize = null;
  var lastPlace = 1;
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    lastSize = a.size;
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                   .replace("{{NAME}}", a.user)
                   .replace("{{LANGUAGE}}", a.language)
                   .replace("{{SIZE}}", a.size)
                   .replace("{{LINK}}", a.link);
    answer = jQuery(answer);
    jQuery("#answers").append(answer);

    var lang = a.language;
    lang = jQuery('<a>'+lang+'</a>').text();
    
    languages[lang] = languages[lang] || {lang: a.language, lang_raw: lang, user: a.user, size: a.size, link: a.link};
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  var langs = [];
  for (var lang in languages)
    if (languages.hasOwnProperty(lang))
      langs.push(languages[lang]);

  langs.sort(function (a, b) {
    if (a.lang_raw.toLowerCase() > b.lang_raw.toLowerCase()) return 1;
    if (a.lang_raw.toLowerCase() < b.lang_raw.toLowerCase()) return -1;
    return 0;
  });

  for (var i = 0; i < langs.length; ++i)
  {
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    var lang = langs[i];
    language = language.replace("{{LANGUAGE}}", lang.lang)
                       .replace("{{NAME}}", lang.user)
                       .replace("{{SIZE}}", lang.size)
                       .replace("{{LINK}}", lang.link);
    language = jQuery(language);
    jQuery("#languages").append(language);
  }

}
body {
  text-align: left !important;
  display: block !important;
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#answer-list {
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  float: left;
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#language-list {
  padding: 10px;
  width: 290px;
  float: left;
}

table thead {
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}

table td {
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}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<link rel="stylesheet" type="text/css" href="https://cdn.sstatic.net/Sites/codegolf/all.css?v=ffb5d0584c5f">
<div id="language-list">
  <h2>Shortest Solution by Language</h2>
  <table class="language-list">
    <thead>
      <tr><td>Language</td><td>User</td><td>Score</td></tr>
    </thead>
    <tbody id="languages">

    </tbody>
  </table>
</div>
<div id="answer-list">
  <h2>Leaderboard</h2>
  <table class="answer-list">
    <thead>
      <tr><td></td><td>Author</td><td>Language</td><td>Size</td></tr>
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    <tbody id="answers">

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<table style="display: none">
  <tbody id="answer-template">
    <tr><td>{{PLACE}}</td><td>{{NAME}}</td><td>{{LANGUAGE}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr>
  </tbody>
</table>
<table style="display: none">
  <tbody id="language-template">
    <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr>
  </tbody>
</table>

\$\endgroup\$

251 Answers 251

1
3 4
5
6 7
9
1
\$\begingroup\$

R - 39

Shortest - recursive, until SO:

f=function(i,j){cat(i);f(j,i+j)};f(1,1)

Until n:

i=j=1;for(x in 1:n){print(i);k=i;i=i+j;j=k}

or (a bit vectorized):

a=c(1,1);for(x in 1:n)print((a=c(a[2],sum(a)))[1])

or (without any loop or recursion):

a=c(1,1);sapply(1:n,function(i)a<<-c(a[2],sum(a)))[1,]
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Brainf*ck, 489 466 characters

Granted, this is a bit overkill, not to mention that it could be optimised a lot. I will get to improving it tomorrow, since it's too late today.

EDIT: Improved by a few bytes by putting stuff closer together on the tape.

++++++>++++++++++>+>>>>>>>>>+<<<<<<<<<<<[->>[>>+>+<<<-]>>>[<<<+>
>>-]<<+>[<->[>++++++++++<[->-[>+>>]>[+[-<+>]>+>>]<<<<<]>[-]+++++
+++[<++++++>-]>[<<+>>-]>[<<+>>-]<<]>]<[->>++++++++[<++++++>-]]<[
.[-]<]>>>>>>>>[->+<<<<<<<<<<+>>>>>>>>>]>[-<+>]<<<<<<<<<<<.>>>>>>
>>>>[>>+>+<<<-]>>>[<<<+>>>-]<<+>[<->[>++++++++++<[->-[>+>>]>[+[-
<+>]>+>>]<<<<<]>[-]++++++++[<++++++>-]>[<<+>>-]>[<<+>>-]<<]>]<[-
>>++++++++[<++++++>-]]<[.[-]<]<<<<<<<<<<[->+>>>>>>>>+<<<<<<<<<]>
[-<+>]<<.<]

(With added newlines for readability)

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Oration, 135 bytes

I believe that this is "optimal"... takes a deep breath here we go!

Inhale
Start a function f with n
If n<2
Return n
Backtracking
Inhale
Here
Literally, f(n-2)+f(n-1)
I'm done
Listen
Invoke f with number

The little ~> is input. This outputs the (input)th Fibonacci number. This transpiles to (in Python):

def f(n):
    if n<2:
        return  n
    return f(n-2)+f(n-1) 
print(f(eval(input("~>"))))
| improve this answer | |
\$\endgroup\$
  • 1
    \$\begingroup\$ Why is the transpiled Python code not golfed D: \$\endgroup\$ – Downgoat Feb 2 '16 at 4:01
1
\$\begingroup\$

Oracle SQL 9.2, 80 bytes

SELECT ROUND(POWER((1+SQRT(5))/2,LEVEL-1)/SQRT(5))FROM DUAL CONNECT BY LEVEL<:1;
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Lua, 51 bytes

function f(n) return n<2 and n or f(n-1)+f(n-2)end

It creates a function called f(n), that takes an input (n). If n = 1, returns n. This function uses recursion.

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

beeswax, 12 bytes (sequence), 42 bytes (n-th Fib.)

Beeswax is newer than the question, so no competition here.

Fibonacci sequence.

p{N<P{*
>~+d

No promotion to higher bit widths implemented in my solution, so 64-bit overflow starts at the 93rd or 92nd Fibonacci number, depending if you start counting your sequence at 0 or 1:

0  
1  
1  
2  
3  
5  
8  
13 
21 
34 
55 
89 
.
.
.
4660046610375530309
7540113804746346429
12200160415121876738   ← 93rd Fibonacci number
1293530146158671551    ← 1st. 64-bit overflow/wraparound
13493690561280548289

N-th Fibonacci number:

;{#'<>~P~L#MM@>+@'p@{;
  _TNX~P~K#{; d~@M<

The same limit applies to this solution.

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

CJam, noncompeting, 11 bytes

0X{_@+}q~*;
| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ F(0) = 0. You should eliminate the backslash. \$\endgroup\$ – Dennis Mar 2 '16 at 15:40
  • \$\begingroup\$ Ah I was assuming that we were starting from 1,1..... so I guess this is a good convention since it saves a byte :) \$\endgroup\$ – A Simmons Mar 2 '16 at 16:18
  • \$\begingroup\$ People start the Fibonacci sequence at different values, so F(0) = 0 may or may not be defined. However, when it comes to indexing, F(1), F(2) = 1, since a lot of the sequence's properties depend on that. \$\endgroup\$ – Dennis Mar 2 '16 at 16:29
1
\$\begingroup\$

DUP, 10 bytes

1$[^^+2!]!

Try it here.

An infinite stream that leaves results on stack. Use the Step button to avoid setting off the infinite loop.

Explanation

1$         {start w/ 2 1's}
  [     ]! {execute lambda}
   ^^      {take top 2 items on stack}
     +     {add them}
      2!   {self recurse!}
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Gogh, 10 bytes

¹Ƥ{Ƥ÷®+Ø}x

Executed from the command line like this:

$ ./gogh "" "¹Ƥ{Ƥ÷®+Ø}x"

Explanation

¹       “ Push two ones to the stack.                 ”
Ƥ       “ Print the TOS.                              ”
{       “ Open a code block.                          ”
 Ƥ      “ Print the TOS.                              ”
 ÷      “ Duplicate the TOS.                          ”
 ®      “ Rotate the stack leftward.                  ”
 +      “ Destructively add the TOS to the STOS.      ”
 Ø      “ Loop all preceding code (within the block). ”
}       “ Close a code block.                         ”
x       “ Execute the TOS.                            ”
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Scratch, 106 characters

This isn't impressive at all but someone had to do it.

scratch blocks

when gf clicked
add[1]to[f v
forever
 add((item[last v]of[f v])+(item((length of[f v])-(1))of[f v]))to[f v

scratchblocks2 render

Fairly bog-standard solution. "f" is a list which starts off empty. Runs as long as you let it.

Since it's not easy to define what is and isn't a "character" in Scratch I've used the forum plugin's formatting. This allows me to cheat off some additional characters (scratchblocks2 is very lenient with dropping closing parenthesis, "end"s, and shaving off whitespace here and there)

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Alpax, 5 bytes (non-competing)

Non-competing since the language postdates the challenge. Code:

⇇+
1¹

Yes, that's right mates. My newest invention, which is more mathematically based than 05AB1E. This language uses a lot of recursion, so be aware. This is a bit like a stack based language, but a little bit different. The elaborated version of the above code is:

a(n) = ⇇+
a(0) = 1, a(1) = 1

Explanation:

⇇ is short for pushing a(n - 1), a(n - 2)
+ adds both functions up.

It then implicitly prints the result of a(n), whereas n is the input.

Uses the Alpax encoding.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ Alpax doesn't exist anymore. \$\endgroup\$ – user85052 Dec 24 '19 at 12:43
  • \$\begingroup\$ The Alpax repo is gone. Umm, is this language converted into Oasis? \$\endgroup\$ – Third-party 'Chef' May 11 at 8:32
  • \$\begingroup\$ @Λ̸̸ Alpax is/was a different language and a public repository is not available anymore. Oasis was another attempt at a golfing language specialized in sequences, which became a bit more successful and 'took over' the place of Alpax. \$\endgroup\$ – Adnan May 11 at 16:17
1
\$\begingroup\$

PlatyPar, 7 bytes

0A1wAC+

Try it online!

Explanation:

0A1       ## push first two Fibonacci numbers to stack and print them
    w     ## while last item != 0 (always true)
     A      ## print the most recently calculated Fibonacci number
      C+    ## push the sum of the last two items of the stack

This one is a sequence.

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

C#: 83 69 68 66 58 53 51

I used a nasty trinary and recursive lambda expression to achieve this one.

Source: StackOverflow

Func<ulong,ulong> f=null;f=x=>x<2?x:f(x-2)+f(x-1);

Usage:

    public static void Main()
    {
        // Recursive lambda expression...
        Func<ulong, ulong> f = null;
        f = x => (x < 2) ? x : f(x - 2) + f(x - 1);

        Console.WriteLine("Please enter a whole number to obtain the Fibonacci sequence number for:");
        string value = Console.ReadLine();

        long numValue;
        if(UInt64.TryParse(value, out numValue))
            Console.WriteLine(f(numValue));

        Console.WriteLine("Press any key to end the program.");
        Console.ReadKey();
    }
| improve this answer | |
\$\endgroup\$
  • 2
    \$\begingroup\$ You don't have no support negative indices. Also, the "ternary" conditional operator isn't nasty if you use it right. :-) \$\endgroup\$ – Chris Jester-Young Apr 8 '13 at 15:21
  • \$\begingroup\$ That helps, thanks! I don't consider ternaries nasty usually, but in a case like the one I've posted, I would do everything in my power to avoid that getting into a codebase. It gets points for clever/short, but not readable. \$\endgroup\$ – Andrew Gray Apr 8 '13 at 15:28
  • 1
    \$\begingroup\$ lol - I posted mine without ever seeing yours. Funny to see that they're almost identical. :) \$\endgroup\$ – Troy Alford Apr 17 '13 at 17:54
  • 1
    \$\begingroup\$ Yeah, but trying to calculate anything above f(45) will cause either a StackOverflow, or just take forever and some time to calculate. \$\endgroup\$ – Andrew Gray Apr 17 '13 at 18:09
  • 1
    \$\begingroup\$ I don't think you need the parentheses around (n<2) \$\endgroup\$ – Cyoce May 2 '16 at 15:00
1
\$\begingroup\$

Detour, 20 bytes

This one is going for the "infinite sequence" option.

v1vq:$
  $+
p,p^
^ q

Try it online!

Branch 1 takes a number, prints it, adds it with the number from Branch 2, then puts the result in Branch 2
Branch 2 takes a number, feeds it to the addition with branch 1 then puts the original number (not the sum) in Branch 1.

For a better explanation click the link and you'll see it in action.

More "readable" version:

Detour, 267 bytes

:$v  1v   q   # split into branches

          +   # push sum of last 2 fibonacci numbers to branch 2
      {  

  p , p   ^   # print branch 1, merge with branch 3

      }

  ^   q       # push branch 2 into branch 1 for printing and recycling

# 1   2   3

Try it online!

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Maple, 27 bytes

ifelse(n<3,1,f(n-1)+f(n-2))

Usage:

> f := n -> ifelse(n<3,1,f(n-1)+f(n-2));
> f(2);
  1
> f(3);
  2
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Perl 5, 23 bytes

22 bytes, plus 1 for -nE instead of -e.

say$.-=$b+=$.*=-1;redo

Hat tip.

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Sesos, 11 bytes (non-competing)

Not in-place, linear memory.

Hexdump:

0000000: ae8583 ef6bc7 045fe7 b907                         ....k.._...

Size   : 11 byte(s)

Try it online!

Assembler

set numin
set numout
add 1,rwd 1,get    ;setup tape
jmp
  fwd 1
  jmp,sub 1,fwd 1,add 1,fwd 1,add 1,rwd 2,jnz
  rwd 1
  sub 1
  jmp,sub 1,fwd 1,add 1,rwd 1,jnz
  fwd 1
jnz
fwd 2
put
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Java, 71 chars

Single number: (Binet formula, considering 1.62 as the golden ratio))

int f(int n){return(Math.pow(1.62,n)-(Math.pow(-1.62,-n))/Math.sqrt(5)}

I know this isn't surprisingly short, however Math is beautiful and this formula is even more!

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Ruby

Ungolfed, 60 bytes

def fib(prev,nxt)
  x = prev + nxt
  puts x
  fib(nxt,x)
end

Golfed, 33 bytes

def f(a,b)x=a+b;puts x;f(b,x)end

Pretty simple to call, use f(first, next).

| improve this answer | |
\$\endgroup\$
  • 1
    \$\begingroup\$ You can still golf it further. Try taking out the unnecessary whitespace. Also, there are some good tips here \$\endgroup\$ – James Sep 12 '16 at 5:14
  • 1
    \$\begingroup\$ x=a+b;puts x can become puts x=a+b \$\endgroup\$ – Cyoce Dec 11 '16 at 3:26
1
\$\begingroup\$

Java 8 29 bytes

Using Java 8 lambdas. This is a valid statement if there exists a function interface with a method that returns an int and takes an int as a parameter. Also the variable that stores the lambda must be declared as a member (static or non static) of the class it is in so that it can be used recursively.

f=n->n<2?0:f.f(n-1)+f.f(n-2);

Ungolfed:

@FunctionalInterface interface F
{
    int f(int n);
}

public class Main
{
    static F f;

    public static void main(String[] args)
    {
        f=n->n<2?0:f.f(n-1)+f.f(n-2);
    }
}
| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Prismatic, 113 bytes (can be smaller)

right wideness wideness left forward up vertex longness backward right vertex tallness forward down vertex vertex

Inspired by Brainfuck, Cubix and Hexagony.

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Python, 75 bytes

a=[1,1]
while True:
    a.append(a[-1]+a[-2])
    a.pop(0)
    print(a[-2])

Yes, I know, way too big, but I don't know golfing languages that well.

| improve this answer | |
\$\endgroup\$
  • 1
    \$\begingroup\$ 1) while True can be replaced with while 1. 2) You only need one space of indentation. 3) The while loop contents can be replaced with print(a[0]);a=[a[1],sum(a)] (on the same line as the while statement). 4) The parentheses on the print call can be removed if you're using Python 2. With all these tricks applied: a=[1,1]\nwhile 1:print(a[0]);a=[a[1],sum(a)] (replace the '\n' with a literal newline). \$\endgroup\$ – Mego Nov 17 '16 at 13:41
  • \$\begingroup\$ If you take Mego's approach you can replace a=[a[1],sum(a)] with a=a[1],sum(a) to save two bytes. This works because the comma creates an implicit tuple rather than a literal list. \$\endgroup\$ – Ad Hoc Garf Hunter Nov 17 '16 at 13:56
  • \$\begingroup\$ The same can also be done with a=[1,1]. It can be shortened to a=1,1 \$\endgroup\$ – Ad Hoc Garf Hunter Nov 17 '16 at 14:00
1
\$\begingroup\$

Ruby (as function) 31 bytes

->n{a,b=1,0;n.times{a=b+b=a};b}
| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ This is byte-per-byte exactly the same as another answer. \$\endgroup\$ – Addison Crump Jan 18 '17 at 0:28
  • \$\begingroup\$ Yes, it was. I commented on the other answer and wrote mine before the original author accepted my suggestion. Now I am only leaving the function, because I could not find any ruby function in 5 randomly-sorted pages of answers. \$\endgroup\$ – G B Jan 19 '17 at 7:13
  • \$\begingroup\$ @VoteToClose Duplicate answers are allowed. \$\endgroup\$ – James Jan 19 '17 at 7:17
  • \$\begingroup\$ My code was mostly stolen from the other answer, with a little improvement (which is now also in the original post), and my answer was written much later. I am leaving the function because I could not find another. \$\endgroup\$ – G B Jan 19 '17 at 7:28
1
\$\begingroup\$

Forth, 27 bytes

Prints them forever (until it exceeds the maximum integer).

: f over . 2dup + recurse ;

Try it online

Returns the nth Fibonacci number. This assumes I can leave garbage on the stack (the result is still on top), 30 bytes:

: f 1 0 rot 0 DO 2dup + LOOP ;

Try it online

| improve this answer | |
\$\endgroup\$
1
\$\begingroup\$

Alice, 11 bytes

This was a collaborative golfing effort with Sp3000.

1 \ O
,+{.3

Try it online!

This prints the Fibonacci sequence indefinitely, starting from 1,1, one integer on a line. Unfortunately, it's horrible in terms of memory, because it leaks one stringified copy of each number in the sequence. The things you do for bytes...

Explanation

1   Push 1 to initialise the sequence. There's already an implicit zero underneath.
\   Reflect to NE. Switch to Ordinal.
    Immediately reflect off top boundary, move SE.

    The remainder of the program runs in an infinite loop. At this point of the loop
    there's the current number F_n of the sequence on top of the stack, and the 
    previous number F_n-1 is below.

                                                            Stack:
                                                            [... F_n-1 F_n] 
.   Implicitly convert F_n to a string and duplicate it.    [... F_n-1 "F_n" "F_n"]
    Reflect off bottom boundary, move NE.
O   Output F_n with a trailing linefeed.                    [... F_n-1 "F_n"]
    Reflect off top right corner, move back SW.
.   Make another copy of F_n. (We don't need this one.)     [... F_n-1 "F_n" "F_n"]
    Reflect off bottom boundary, move NW.
\   Reflect to S. Switch to Cardinal.
{   Turn 90 degrees left, i.e. east.
.   Implicitly convert F_n to an integer and duplicate it.  [... F_n-1 "F_n" F_n F_n]
3   Push 3.                                                 [... F_n-1 "F_n" F_n F_n 3]
,   Pull up the third stack element, which is F_n-1.        [... "F_n" F_n F_n F_n-1]
+   Add F_n and F_n-1.                                      [... "F_n" F_n F_n+1]  
{   Turn 90 degrees left, i.e. north.
\   Reflect to SE. Switch to Ordinal.

    After this point, the loop repeats.
| improve this answer | |
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Taxi, 864 bytes

1 is waiting at Starchild Numerology.1 is waiting at Starchild Numerology.Go to Starchild Numerology:W 1 L 2 R 1 L 1 L 2 L.Pickup a passenger going to Sunny Skies Park.Pickup a passenger going to Cyclone.Go to Sunny Skies Park:W 1 R.[a]Go to Cyclone:N 1 L.Pickup a passenger going to The Babelfishery.Pickup a passenger going to Addition Alley.Go to Fueler Up:N 2 R, 2 R.Go to The Babelfishery:S.Pickup a passenger going to Post Office.Go to Post Office:N 1 L 1 R.Go to Sunny Skies Park:S 1 R 1 L 1 R.Pickup a passenger going to Cyclone.Go to Cyclone:N 1 L.Pickup a passenger going to Addition Alley.Pickup a passenger going to Cyclone.Go to Addition Alley:N 2 R 1 R.Pickup a passenger going to Sunny Skies Park."," is waiting at Writer's Depot.Go to Writer's Depot:N 1 L 1 L.Pickup a passenger going to Post Office.Go to Sunny Skies Park:N 2 R.Switch to plan "a".

Try it online!

Ungolfed:

1 is waiting at Starchild Numerology.
1 is waiting at Starchild Numerology.
Go to Starchild Numerology: west 1st left 2nd right 1st left 1st left 2nd left.
Pickup a passenger going to Sunny Skies Park.
Pickup a passenger going to Cyclone.
Go to Sunny Skies Park: west 1st right.
[a]
Go to Cyclone: north 1st left.
Pickup a passenger going to The Babelfishery.
Pickup a passenger going to Addition Alley.
Go to Fueler Up: north 2nd R, 2nd right.
Go to The Babelfishery: south.
Pickup a passenger going to Post Office.
Go to Post Office: north 1st left 1st right.
Go to Sunny Skies Park: south 1st right 1st left 1st right.
Pickup a passenger going to Cyclone.
Go to Cyclone: north 1st left.
Pickup a passenger going to Addition Alley.
Pickup a passenger going to Cyclone.
Go to Addition Alley: north 2nd right 1st right.
Pickup a passenger going to Sunny Skies Park.
"," is waiting at Writer's Depot.
Go to Writer's Depot: north 1st left 1st left.
Pickup a passenger going to Post Office.
Go to Sunny Skies Park: north 2nd right.
Switch to plan "a".
| improve this answer | |
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1
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Braingolf, 23 bytes

1!_# @.!_[# @!+!_<1+>];

Try it online!

| improve this answer | |
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  • \$\begingroup\$ 17 bytes \$\endgroup\$ – Skidsdev Jun 16 '17 at 9:20
  • \$\begingroup\$ 14 bytes \$\endgroup\$ – Skidsdev Jun 16 '17 at 9:23
  • \$\begingroup\$ 8 bytes for output the nth number \$\endgroup\$ – Skidsdev Jun 16 '17 at 9:35
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Joy, 45 bytes

DEFINE f ==[2<][][[1 - f][2 - f]cleave+]ifte.

Try it online! Zero-indexed. Example usage: 6 f yields 8.

[2<]                         ifte . if the top stack element is less than two  
    []                            . then do nothing
      [              cleave ]     . else duplicate the element and apply two functions
                           +      . and sum the results
       [1 - f][2 - f]             . where the functions compute the two previous Fibonacci numbers

Alternative (same byte count):

DEFINE f ==[2<][][dup 1 - f swap 2 - f+]ifte.
| improve this answer | |
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1
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cQuents, 6 bytes

=1:z+y

Try it online!

This works both with and without input - it prints the sequence without input, and the nth item (1-indexed) with input n.

For 0, 1, 1, ... version, 8 bytes:

=0,1:z+y

Try it online!

Explanation

=1      Set first item in sequence to 1
  :     Mode: Sequence 1 (prints sequence with no input, or nth item with input n
   z+y  Each term equals the previous two terms added together (defaults to 0)

I really, really like the way this language is going :)

| improve this answer | |
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  • \$\begingroup\$ Note current version uses Z and Y instead of z and y \$\endgroup\$ – Stephen Feb 1 '19 at 4:54
1
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ReRegex, 50 bytes.

(0+),(0+):0/$1,$2,$1$2:/.*?(0+),0+:$/$1/0,0:#input

0 indexed. Takes input and gives output via Unary.

Try it online!

About the Program

ReRegex was designed to be much like an advanced version of ///. It offers the same very basic concept of repeatedly doing string match and replace operations. However, that's where the similarities end. ReRegex instead uses a list of match and replace operations, separated by /s, to perform in a loop, and the original string to effect. The Regexes will continue being performed on the original string until a constant state is achieved, at which point the program will dump the string to STDOUT.

This program in particular is just 2 regular expressions and then the input with some default values.

(0+),(0+):0  -> $1,$2,$1$2:
.*?(0+),0+:$ -> $1

And the input is formatted with;

0,0:#input

ReRegex defaultly replaces #input with whatever is passed to the program on STDIN.

For an example, let's say 00000 is passed to STDIN. First, the "Memory" looks like this:

0,0:00000

In the first loop, the regex (0+),(0+):0 is matched, the replace then creates the next itteration of the fibonnachi sequence.

0,0,00:0000

And in doing so, it also pops one of the 0's off, which is why :0 is at the tail end of the match, but not the replace. This then happens 4 more times in a row.

0,0,00,000,00000,00000000,0000000000000:

Now that first regex doesn't match, as there's no more :0 at the end, so we're almost at a stable end point. Now that there's nothing after :, .*?(0+),0+:$ matches, and all it does is clear all data but the second last group of 0s.

00000000

Now, nothing else matches, so it's outputted.

| improve this answer | |
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