Print the N-bonacci sequence

Question

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

Answer 1

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.

Answer 2

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

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Answer 3

Haskell, 56 bytes

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

Answer 4

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

Answer 5

Javascript ES6/ES2015, 107 97 85 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

Answer 6

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.

Answer 7

Jelly, 12 bytes

ḣ³S;
b1Ç⁴¡Uḣ

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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.

Answer 8

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]

Answer 9

Haskell, 47 bytes

q(h:t)=h:q(t++[h+sum t])
n?x=take x$q$1<$[1..n]

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<$ 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]

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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 %.

Answer 10

Husk, 9 bytes

↑§¡ȯΣ↑_B1

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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.

Answer 11

C#, 109 bytes

(n,x)=>{int i,j,k;var y=new int[x];for(i=-1;++i<x;y[i]=i<n?1:k){k=0;for(j=i-n;j>-1&j<i;)k+=y[j++];}return y;}

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---

(n, x) => { 
    int i, j, total; 
    var result = new int[x];
    for (i = -1; ++i < x; ) { //calculate each term one at a time
        total = 0; //value of the current term
        for (j = i - n; j > -1 & j < i;) //sum the last n terms
        {
            total += result[j++]; 
        }
        result[i] = i < n ? 1 : total; //first n terms are always 1 so ignore the total if i < n
    } 
    return result; 
}

Answer 12

Haskell, 46 bytes

g _ 0=[]
g(h:t)n=h:g(t++[sum$h:t])(n-1)

g.g[1]

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This is based on xnor's answer but it employs 1 clever trick.

The \$n\$-bonacci sequence always start with \$n\$ 1s. A more general version of this might start with just any \$n\$ values. And this more general version is what we implement with g. g takes a list of \$n\$ integers and a value \$m\$ and gives us a list of the first \$m\$ terms of this generalized \$n\$-bonacci sequence.

The trick is then that g[1] is a cheap way to generate \$n\$ 1s. Since the sequence starting with [1] is just an endless stream of 1s. So we use g in two ways, and even though g might be slightly longer because it implements something a little more general, it saves bytes because it serves two purposes.

Answer 13

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));}}

Answer 14

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;
}

Answer 15

R, 60 bytes

function(n,m){for(i in 1:m)T[i]=`if`(i>n,sum(T[i-1:n]),1);T}

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Answer 16

Uiua (version 0.0.7), 34 bytes

→(;;)⍥(⊂∶/+↙∶→,⇌.)∶→(-,,)[⍥.-1∶1].

Answer 17

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              

Answer 18

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]

Answer 19

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));
}

Answer 20

Brain-Flak, 144 124 122 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.

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

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Answer 21

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))

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Answer 22

Vyxal , 8 bytes

1ẋ?‡W∑*Ḟ

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1ẋ       # [1] * input
   ‡W∑   # Function summing its inputs
  ?   *  # Set the arity to the input
       Ḟ # Generate an infinite list from the function and the vector of 1s.

Answer 23

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

Answer 24

Perl 6, 52~72 47~67 bytes

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)

Answer 25

MATL, 22 26 bytes

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

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

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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

Answer 26

Perl 6, 38 bytes

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

-> \N, \X {
  (

    {

      @_[
        *-N .. * # previous N values
      ].sum      # added together

      ||     # 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)

Answer 27

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.

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Answer 28

Ruby, 41 bytes

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

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Answer 29

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]}

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Answer 30

K (ngn/k), 26 24 bytes

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

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