# Print the N-bonacci sequence

This isn't very widely known, but what we call the Fibonacci sequence, AKA

1, 1, 2, 3, 5, 8, 13, 21, 34...


is actually called the Duonacci sequence. This is because to get the next number, you sum the previous 2 numbers. There is also the Tribonacci sequence,

1, 1, 1, 3, 5, 9, 17, 31, 57, 105, 193, 355, 653, 1201...


because the next number is the sum of the previous 3 numbers. And the Quadronacci sequence

1, 1, 1, 1, 4, 7, 13, 25, 49, 94, 181, 349, 673...


And everybody's favorite, the Pentanacci sequence:

1, 1, 1, 1, 1, 5, 9, 17, 33, 65, 129...


And the Hexanacci sequence, the Septanacci sequence, the Octonacci sequence, and so on and so forth up to the N-Bonacci sequence.

The N-bonacci sequence will always start with N 1s in a row.

# The Challenge

You must write a function or program that takes two numbers N and X, and prints out the first X N-Bonacci numbers. N will be a whole number larger than 0, and you can safely assume no N-Bonacci numbers will exceed the default number type in your language. The output can be in any human readable format, and you can take input in any reasonable manner. (Command line arguments, function arguments, STDIN, etc.)

As usual, this is Code-golf, so standard loopholes apply and the shortest answer in bytes wins!

# Sample IO

#n,  x,     output
3,  8  --> 1, 1, 1, 3, 5, 9, 17, 31
7,  13 --> 1, 1, 1, 1, 1, 1, 1, 7, 13, 25, 49, 97, 193
1,  20 --> 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
30, 4  --> 1, 1, 1, 1       //Since the first 30 are all 1's
5,  11 --> 1, 1, 1, 1, 1, 5, 9, 17, 33, 65, 129

• Man, I had this idea a while ago and never got around to writing it up. – Morgan Thrapp Jan 29 '16 at 21:43
• My vote button == your avatar – ETHproductions Jan 29 '16 at 23:50
• Wouldn't 3-bonacci be 1, 1, 2, 4, 7 as the third position would be 0 + 1 + 1? ... and so one with the others? – Umbrella Feb 8 at 17:42
• @umbrella No, the tribonacci starts with 3 1s. See my edit to clarify this point. – DJMcMayhem Feb 8 at 17:51

## Boolfuck, 6 bytes

,,[;+]


You can safely assume no N-Bonacci numbers will exceed the default number type in your language.

The default number type in Boolfuck is a bit. Assuming this also extends to the input numbers N and X, and given that N>0, there are only two possible inputs - 10 (which outputs nothing) and 11 (which outputs 1).

, reads a bit into the current memory location. N is ignored as it must be 1. If X is 0, the loop body (surrounded by []) is skipped. If X is 1, it is output and then flipped to 0 so the loop does not repeat.

• Isn't there a standard loophole EXACTLY like this? – Stan Strum Sep 18 '17 at 13:35
• @StanStrum From before or after this answer? – immibis Sep 18 '17 at 22:25
• I believe it came before, let me check it out... Meta Link; First revision was Jan 31, 2016 at 13:44. Wow, nevermind! I was two days off. Although, to be stubborn, the last edit for this was Jan 31, 2016 at 16:06. Soooooo yeah, it's fine in my book – Stan Strum Sep 19 '17 at 1:45

## Python 2, 79 bytes

n,x=input()
i,f=0,[]
while i<x:v=[sum(f[i-n:]),1][i<n];f.append(v);print v;i+=1


Try it online

• Try replacing the last line with exec"v=[sum(f[i-n:]),1][i<n];f+=[v];print v;i+=1;"*x – Cyoce Jan 30 '16 at 5:33

# Pyth, 13

<Qu+Gs>QGEm1Q


Test Suite

Takes input newline separated, with n first.

### Explanation:

<Qu+Gs>QGEm1Q  ##  implicit: Q = eval(input)
u      Em1Q  ##  read a line of input, and reduce that many times starting with
##  Q 1s in a list, with a lambda G,H
##  where G is the old value and H is the new one
+G          ##  append to the old value
s>QG      ##  the sum of the last Q values of the old value
<Q             ##  discard the last Q values of this list

• Wow, that was fast. I barely had time to close my browser before you'd already posted this! – DJMcMayhem Jan 29 '16 at 21:51

g l=sum l:g(sum l:init l)
n#x|i<-1<$[1..n]=take x$i++g i


Usage example: 3 # 8-> [1,1,1,3,5,9,17,31].

How it works

i<-1<$[1..n] -- bind i to n copies of 1 take x -- take the first x elements of i++g i -- the list starting with i followed by (g i), which is sum l: -- the sum of it's argument followed by g(sum l:init l) -- a recursive call to itself with the the first element -- of the argument list replaced by the sum  • Shouldn't that be tail l instead of init l? – proud haskeller Jan 31 '16 at 20:49 • @proudhaskeller: it doesn't matter. we keep the last n elements int the list. There's no difference between removing from the end and adding to the front and the other way around, i.e. removing from the front and adding to the end, because the initial list is made up of only 1s. – nimi Jan 31 '16 at 21:19 • Oh, I get it. That's a nifty way to replace ++[] by :! – proud haskeller Jan 31 '16 at 21:26 • @proudhaskeller: yes, exactly! – nimi Jan 31 '16 at 21:30 ## Python 2, 55 bytes def f(x,n):l=[1]*n;exec"print l[0];l=l[1:]+[sum(l)];"*x  Tracks a length-n window of the sequence in the list l, updated by appending the sum and removing the first element. Prints the first element each iteration for x iterations. A different approach of storing all the elements and summing the last n values gave the same length (55). def f(x,n):l=[1]*n;exec"l+=sum(l[-n:]),;"*x;print l[:x]  # Javascript ES6/ES2015, 1079785 80 Bytes Thanks to @user81655, @Neil and @ETHproductions for save some bytes (i,n)=>eval("for(l=Array(i).fill(1);n-->i;)l.push(eval(l.slice(-i).join+));l")  try it online Test cases: console.log(f(3, 8))// 1, 1, 1, 3, 5, 9, 17, 31 console.log(f(7, 13))// 1, 1, 1, 1, 1, 1, 1, 7, 13, 25, 49, 97, 193 console.log(f(5, 11))// 1, 1, 1, 1, 1, 5, 9, 17, 33, 65, 129  • Nice. A couple of golfing tips: for is always better than while, x.split('') -> [...x], ~~a -> +a, n-=1 -> n--, if you enclose the entire function body in an eval you don't need to write return. Also, even shorter than [...'1'.repeat(i)] is Array(i).fill(1) and you can remove the ~~ from a and b. And you're allowed to remove the f=. – user81655 Jan 29 '16 at 23:51 • This is what it looks like with my tips (85 bytes): (i,n)=>eval("for(l=Array(i).fill(1);n-->i;)l.push(l.slice(-i).reduce((a,b)=>a+b));l"). I changed the order of statements, combined the n-- into n-i and removed l from the arguments to save a few extra bytes. – user81655 Jan 30 '16 at 0:13 • @user81655 I don't get the eval saving; (i,n)=>{for(l=Array(i).fill(1);n-->i;)l.push(l.slice(-i).reduce((a,b)=>a+b));return l} is still 85 bytes. – Neil Jan 30 '16 at 0:17 • @Neil Looks like 86 bytes to me... – user81655 Jan 30 '16 at 0:21 • l.slice(-i).reduce((a,b)=>a+b) => eval(l.slice(-i).join+) – ETHproductions Jan 30 '16 at 0:52 ## ES6, 66 bytes (i,n)=>[...Array(n)].map((_,j,a)=>a[j]=j<i?1:j-i?s+=s-a[j+~i]:s=i)  Sadly map won't let you access the result array in the callback. • Save a byte by currying the parameters. – Shaggy May 11 '17 at 11:36 # Jelly, 12 bytes ḣ³S; b1Ç⁴¡Uḣ  Try it online! ### How it works b1Ç⁴¡Uḣ Main link. Left input: n. Right input: x. b1 Convert n to base 1. ¡ Call... Ç the helper link... ⁴ x times. U Reverse the resulting array. ḣ Take its first x elements. ḣ³S; Helper link. Argument: A (list) ḣ³ Take the first n elements of A. S Compute their sum. ; Prepend the sum to A.  # C++11, 360 bytes Hi I just like this question. I know c++ is a very hard language to win this competition. But I'll thrown a dime any way. #include<vector> #include<numeric> #include<iostream> using namespace std;typedef vector<int>v;void p(v& i) {for(auto&v:i)cout<<v<<" ";cout<<endl;}v b(int s,int n){v r(n<s?n:s,1);r.reserve(n);for(auto i=r.begin();r.size()<n;i++){r.push_back(accumulate(i,i+s,0));}return r;}int main(int c, char** a){if(c<3)return 1;v s=b(atoi(a[1]),atoi(a[2]));p(s);return 0;}  I'll leave this as the readable explanation of the code above. #include <vector> #include <numeric> #include <iostream> using namespace std; typedef vector<int> vi; void p(const vi& in) { for (auto& v : in ) cout << v << " "; cout << endl; } vi bonacci(int se, int n) { vi s(n < se? n : se, 1); s.reserve(n); for (auto it = s.begin(); s.size() < n; it++){ s.push_back(accumulate(it, it + se, 0)); } return s; } int main (int c, char** v) { if (c < 3) return 1; vi s = bonacci(atoi(v[1]), atoi(v[2])); p(s); return 0; }  • Welcome to Programming Puzzles and Code Golf. This is a good answer, however I have noticed that you have lots of whitespace, and variable and function names that are longer than 1 character long. As it stands, this is a good readable version of your code, but you should add a golfed version. When you do, I will give you an upvote, but until it is golfed I will not. – wizzwizz4 Jan 30 '16 at 13:28 • @wizzwizz4 Hi, added a golfed version of the code above. I left the ungolfed code around to let people see how I did it. Besides I like to read a function bonacci that returns vi which still sounds like vibonacci. I do feel I should not make the main function shorter because the standardard mandates using int main(int, char**) as entry point of the program. Further I believe all variables are max 1 character long and all non significant whitespaces are removed. – hetepeperfan Jan 30 '16 at 14:36 • This is not code-"comply with the standards". This is code-golf. We manipulate and take advantage of our languages. If any variables are ints, remove the int. If any functions are called foo, call them f. Be brutal; ignore the standard and exploit the compiler. That is how you golf. – wizzwizz4 Jan 30 '16 at 16:11 • Puns and nice code belong in the ungolfed code only. But feel free to keep them there; actually, it is recommended to. But be really, really mean to the compiler when you golf your code. Get it as small as possible no matter what. (Oh, and here's the +1 I promised!) – wizzwizz4 Jan 30 '16 at 16:12 • @wizzwizz4 Is removing "int" valid? I thought implied int won't run. – DJMcMayhem Jan 30 '16 at 20:18 # Haskell, 47 bytes q(h:t)=h:q(t++[h+sum t]) n?x=take x$q$1<$[1..n]


Try it online!

<$ might have been introduced into Prelude after this challenge was posted. Haskell, 53 bytes n%i|i>n=sum$map(n%)[i-n..i-1]|0<1=1
n?x=map(n%)[1..x]


Try it online!

Defines the binary function ?, used like 3?8 == [1,1,1,3,5,9,17,31].

The auxiliary function % recursively finds the ith element of the n-bonacci sequence by summing the previous n values. Then, the function ? tabulates the first x values of %.

• Old answer, but do you mean "The auxiliary function %"? – Conor O'Brien Nov 26 '18 at 1:02
• Switching the guards will turn i<=n into i>n. – Ørjan Johansen Nov 26 '18 at 2:38
• @ØrjanJohansen I noticed that too when editing, though looking back the whole method seems bad, so I might just re-do the whole golf. – xnor Nov 26 '18 at 2:42

# APL, 21

{⍵↑⍺{⍵,+/⍺↑⌽⍵}⍣⍵+⍺/1}


This is a function that takes n as its left argument and x as its right argument.

Explanation:

{⍵↑⍺{⍵,+/⍺↑⌽⍵}⍣⍵+⍺/1}
⍺/1  ⍝ begin state: X ones
+     ⍝ identity function (to separate it from the ⍵)
⍺{         }⍣⍵     ⍝ apply this function N times to it with X as left argument
⍵,               ⍝ result of the previous iteration, followed by...
+/              ⍝ the sum of
⍺↑            ⍝ the first X of
⌽          ⍝ the reverse of
⍵         ⍝ the previous iteration
⍵↑                    ⍝ take the first X numbers of the result


Test cases:

      ↑⍕¨ {⍵↑⍺{⍵,+/⍺↑⌽⍵}⍣⍵+⍺/1} /¨ (3 8)(7 13)(1 20)(30 4)(5 11)
1 1 1 3 5 9 17 31
1 1 1 1 1 1 1 7 13 25 49 97 193
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1
1 1 1 1 1 5 9 17 33 65 129


# Python 3, 59

Saved 20 bytes thanks to FryAmTheEggman.

Not a great solution, but it'll work for now.

def r(n,x):f=[1]*n;exec('f+=[sum(f[-n:])];'*x);return f[:x]


Also, here are test cases:

assert r(3, 8) == [1, 1, 1, 3, 5, 9, 17, 31]
assert r(7, 13) == [1, 1, 1, 1, 1, 1, 1, 7, 13, 25, 49, 97, 193]
assert r(30, 4) == [1, 1, 1, 1]


# Java, 82 + 58 = 140 bytes

Function to find the ith n-bonacci number (82 bytes):

int f(int i,int n){if(i<=n)return 1;int s=0,q=0;while(q++<n)s+=f(i-q,n);return s;}


Function to print first k n-bonacci number (58 bytes):

(k,n)->{for(int i=0;i<k;i++){System.out.println(f(i,n));}}


# Brain-Flak, 144124 122 bytes

-20 bytes thanks to Nitroden

This is my first Brain-Flak answer, and I'm sure it can be improved. Any help is appreciated.

(([{}]<>)<{({}(()))}{}>)<>{({}[()]<<>({<({}<({}<>)<>>())>[()]}{})({}<><({({}<>)<>}<>)>)<>>)}{}<>{({}<{}>())}{}{({}<>)<>}<>


Try it online!

# Pari/GP, 46 bytes

The generating function of the sequence is:

$$\frac{(n-1)x^n}{x^{n+1}-2x+1}-\frac{1}{x-1}$$

(n,m)->Vec(n--/(x-(2-1/x)/x^n)-1/(x-1)+O(x^m))


Try it online!

# Julia, 78 bytes

f(n,x)=(z=ones(Int,n);while endof(z)<x push!(z,sum(z[end-n+1:end]))end;z[1:x])


This is a function that accepts two integers and returns an integer array. The approach is simple: Generate an array of ones of length n, then grow the array by adding the sum of the previous n elements until the array has length x.

Ungolfed:

function f(n, x)
z = ones(Int, n)
while endof(z) < x
push!(z, sum(z[end-n+1:end]))
end
return z[1:x]
end


# MATL, 22 26 bytes

1tiXIX"i:XK"tPI:)sh]K)


This uses current release (10.2.1) of the language/compiler.

Try it online!

A few extra bytes :-( due to a bug in the G function (paste input; now corrected for next release)

### Explanation

1tiXIX"      % input N. Copy to clipboard I. Build row array of N ones
i:XK         % input X. Build row array [1,2,...X]. Copy to clipboard I
"            % for loop: repeat X times. Consumes array [1,2,...X]
t          % duplicate (initially array of N ones)
PI:)       % flip array and take first N elements
sh         % compute sum and append to array
]            % end
K)           % take the first X elements of array. Implicitly display


# Perl 6, 38 bytes

->\N,\X{({@_[*-N..*].sum||1}...*)[^X]} # 38 bytes

-> \N, \X {
(

{

@_[
*-N .. * # previous N values

||     # if that produces 0 or an error
1      # return 1

} ... *  # produce an infinite list of such values

)[^X]      # return the first X values produced
}


### Usage:

# give it a lexical name
my &n-bonacci = >\N,\X{…}

for ( (3,8), (7,13), (1,20), (30,4), (5,11), ) {
say n-bonacci |@_
}

(1 1 1 3 5 9 17 31)
(1 1 1 1 1 1 1 7 13 25 49 97 193)
(1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1)
(1 1 1 1)
(1 1 1 1 1 5 9 17 33 65 129)


# C, 132 bytes

The recursive approach is shorter by a couple of bytes.

k,n;f(i,s,j){for(j=s=0;j<i&j++<n;)s+=f(i-j);return i<n?1:s;}main(_,v)int**v;{for(n=atoi(v[1]);k++<atoi(v[2]);)printf("%d ",f(k-1));}


## Ungolfed

k,n; /* loop index, n */

f(i,s,j) /* recursive function */
{
for(j=s=0;j<i && j++<n;) /* sum previous n n-bonacci values */
s+=f(i-j);
return i<n?1:s; /* return either sum or n, depending on what index we're at */
}

main(_,v) int **v;
{
for(n=atoi(v[1]);k++<atoi(v[2]);) /* print out n-bonacci numbers */
printf("%d ", f(k-1));
}


# Husk, 9 bytes

↑§¡ȯΣ↑_B1


Try it online!

Starts from the Base-1 representation of N (simply a list of N ones) and ¡teratively sums (Σ) the last (↑_) N elements and appends the result to the list. Finally, takes (↑) the first X numbers in this list and returns them.

# Ruby, 41 bytes

->a,b{r=[1]*a;b.times{z,*r=r<<r.sum;p z}}


Try it online!

# R, 68 bytes

function(n,x){a=1+!1:n;for(i in n+1:x){a[i]=sum(a[(i-n:1)])};a[1:x]}


Try it online!

# K (ngn/k), 26 24 bytes

{(y-x){y,+/x#y}[-x]/x#1}


Try it online!

sub a($n,$x){EVAL("1,"x$n~"+*"x$n~"...*")[^$x]}  Requires the module MONKEY-SEE-NO-EVAL, because of the following error: ===SORRY!=== Error while compiling -e EVAL is a very dangerous function!!! (use MONKEY-SEE-NO-EVAL to override, but only if you're VERY sure your data contains no injection attacks) at -e:1 $ perl6 -MMONKEY-SEE-NO-EVAL -e'a(3,8).say;sub a($n,$x){EVAL("1,"x$n~"+*"x$n~"...*")[^$x]}' (1 1 1 3 5 9 17 31)  • Anyone know of a way to turn off strict mode, etc? – andlrc Jan 29 '16 at 23:34 • I think if you use a pre-christmas 2015 Perl 6 release, it doesn't enforce monkey-see-no-eval. – Batman Jan 30 '16 at 17:29 # PHP, 78 bytes for(list(,$n,$x)=$argv;$i<$x;print${$i++}." ")$s+=$$i=i<n?1:$$d+$s-=${$d++};


Try it online!

-4 Bytes using PHP>=7.1 [,$n,$x] instead of list(,$n,$x)

# Jq 1.5, 67 bytes

def C:if length>X then.[:X]else.+=[.[-N:]|add]|C end;[range(N)|1]|C


Assumes input provided by N and X e.g.

def N: 5;
def X: 11;


Expanded

def C:                        # . is current array
if length>X               # stop when array is as long as X
then .[:X]                # return first X elements
else .+=[.[-N:]|add] | C  # recursively add sum of last N elements to array
end
;
[range(N)|1]                # initial state
| C


Try it online!

# J, 31 bytes

]{.(],[:+/[{.])^:(-@[](1#~[))


Ungolfed:

] {. (] , [: +/ [ {. ])^:(-@[](1 #~ [))


## explanation

Fun times with the power verb in its gerund form:

(-@[](1 #~ [)) NB. gerund pre-processing


Breakdown in detail:

• ] {. ... Take the first <right arg> elements from all this stuff to the right that does the work...
• <left> ^: <right> apply the verb <left> repeatedly <right> times... where <right> is specified by the middle gerund in (-@[](1 #~ [), ie, ], ie, the right arg passed into the function itself. So what is <left>? ...
• (] , [: +/ [ {. ]) The left argument to this entire phrase is first transformed by the first gerund, ie, -@[. That means the left argument to this phrase is the negative of the left argument to the overall function. This is needed so that the phrase [ {. ] takes the last elements from the return list we're building up. Those are then summed: +/. And finally appended to that same return list: ] ,.
• So how is the return list initialized? That's what the third pre-processing gerund accomplishes: (1 #~ [) -- repeat 1 "left arg" number of times.

Try it online!

# Mathematica, 59 bytes

((f@#=1)&/@Range@#;f@n_:=Tr[f[n-#]&/@Range@#];f/@Range@#2)&


You'll probably want to Clear@f between function calls. Arguments are n,x, just like the test cases.

# Tidy, 36 bytes

{x,n:n^recur(*tile(x,c(1)),sum@c,x)}


Try it online!

## Explanation

{x,n:n^recur(*tile(x,c(1)),sum@c,x)}
{x,n:                              }   lambda taking parameters x and n
n^                                take the first n terms of...
recur(                     )        a recursive function
*tile(x,c(1)),                whose seed is x 1s
sum@c,          taking the sum of each window
x         with a window size of x


# Japt, 18 bytes

@ZsVn)x}gK=Vì1;K¯U


Try it online!

Explanation:

         K=Vì1        :Start with n 1s in an array K
@      }gK            :Extend K to at least x elements by setting each new element to:
x               : The sum of
ZsVn                 : The previous n elements
;       :Then
K¯U    :Return the first n elements of K