Fibonacci n-step number sequences: Difference between revisions

<lang d>import std.stdio, std.algorithm, std.range, std.conv, std.functional;

void main() {

int[] head;

int fibber(in size_t n) /*nothrow*/ {

alias memoize!fibber f;

if (n < head.length)

return head[n];

return iota(n - head.length, n).map!f().reduce!q{a + b}();

}

head = [1, 1];

iota(10).map!fibber().writeln();

head = [2, 1];

iota(10).map!fibber().writeln();

auto prefixes = "fibo tribo tetra penta hexa hepta octo nona deca";

foreach (n, name; zip(iota(2, 11), prefixes.split())) {

head = [1] ~ iota(n-1).map!q{2 ^^ a}().array();

const items = iota(15).map!(i => text(fibber(i)))().join(" ");

writefln("n=%2d, %5snacci -> %s ...", n, name, items);

}

}</lang>

{{out}}

<pre>[1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

[2, 1, 2, 3, 5, 8, 13, 21, 34, 55]

n= 2, fibonacci -> 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 ...

n= 3, tribonacci -> 1 1 2 4 6 10 16 26 42 68 110 178 288 466 754 ...

n= 4, tetranacci -> 1 1 2 4 7 11 18 29 47 76 123 199 322 521 843 ...

n= 5, pentanacci -> 1 1 2 4 8 12 19 31 50 81 131 212 343 555 898 ...

n= 6, hexanacci -> 1 1 2 4 8 16 20 32 52 84 136 220 356 576 932 ...

n= 7, heptanacci -> 1 1 2 4 8 16 32 33 53 86 139 225 364 589 953 ...

n= 8, octonacci -> 1 1 2 4 8 16 32 64 54 87 141 228 369 597 966 ...

n= 9, nonanacci -> 1 1 2 4 8 16 32 64 128 88 142 230 372 602 974 ...

n=10, decanacci -> 1 1 2 4 8 16 32 64 128 256 143 231 374 605 979 ...</pre>

===Alternative Version===

The output is similar.