A246937 Number of partitions of n into 5 sorts of parts.

1, 5, 30, 155, 805, 4055, 20455, 102455, 513230, 2567230, 12841130, 64211380, 321082905, 1605444405, 8027354055, 40136925680, 200685295955, 1003427268205, 5017139711105, 25085702537730, 125428529603755, 627142668099880, 3135713425289030, 15678567227192655

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Formula

G.f.: Product_{i>=1} 1/(1-5*x^i).

a(n) ~ c * 5^n, where c = Product_{k>=1} 1/(1-1/5^k) = 1.3152135557353452193080... . - Vaclav Kotesovec, Mar 19 2015

G.f.: Sum_{i>=0} 5^i*x^i/Product_{j=1..i} (1 - x^j). - Ilya Gutkovskiy, Apr 12 2018

Maple

b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
      b(n, i-1) +`if`(i>n, 0, 5*b(n-i, i))))
    end:
a:= n-> b(n$2):
seq(a(n), n=0..25);

Mathematica

(O[x]^20 - 4/QPochhammer[5, x])[[3]] (* Vladimir Reshetnikov, Nov 20 2015 *)
b[n_, i_] := b[n, i] = If[n==0, 1, If[i<1, 0, b[n, i-1] + If[i>n, 0, 5 b[n-i, i]]]];
a[n_] := b[n, n];
a /@ Range[0, 25] (* Jean-François Alcover, Jan 02 2021, after Alois P. Heinz *)

Crossrefs

Column k=5 of A246935.

Sequence in context: A344064 A055298 A104891 * A110155 A122995 A254944

Adjacent sequences: A246934 A246935 A246936 * A246938 A246939 A246940

Keyword

nonn

Author

Alois P. Heinz, Sep 08 2014

Status

approved