> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/perl6-rosettacode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/perl6-rosettacode/programming_tasks/p/partition_function_p.md).

# Partition function P

Not the fastest, but it gets the job done.

```perl
my @P = 1, { p(++$) } … *;
my @i = lazy [\+] flat 1, ( 1..* Z (1..*).map: * × 2 + 1 );
sub p ($n) { sum @P[$n X- @i] Z× (flat (1, 1, -1, -1) xx *) }

put @P[^26];
put @P[6666];
```

#### Output:

```
1 1 2 3 5 7 11 15 22 30 42 56 77 101 135 176 231 297 385 490 627 792 1002 1255 1575 1958
193655306161707661080005073394486091998480950338405932486880600467114423441282418165863
```