A218379 Number of partitions of n into pentagonal parts.

1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 6, 7, 7, 9, 9, 10, 11, 11, 13, 13, 14, 15, 15, 17, 17, 19, 21, 22, 24, 24, 26, 28, 29, 31, 31, 34, 36, 38, 41, 42, 45, 47, 50, 53, 54, 57, 59, 63, 67, 69, 73, 76, 80, 84, 87, 91, 94, 99, 103, 107, 112, 118, 124

Offset

0,6

Links

Seiichi Manyama, Table of n, a(n) for n = 0..10000 (terms 1..100 from Antonio Roldán)

Example

A(15)=5 because 15 = 12+1+1+1 = 5+5+5 = 5+5+1+1+1+1+1 = 5+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 with 12, 5, 1 pentagonal numbers.

Prog

(PARI) {for (n=1, 100, p=truncate((1+sqrt(24*n+1))/6); m=polcoeff(prod(k=1, p, q=(3*k-1)*k/2; sum(h=0, truncate(n/q+1), x^(h*q))), n); write("B218379.txt", n, " ", m))}

Crossrefs

Cf. A000326, A095699.

Sequence in context: A025788 A071806 A025781 * A242763 A018119 A177001

Adjacent sequences: A218376 A218377 A218378 * A218380 A218381 A218382

Keyword

nonn

Author

Antonio Roldán, Oct 27 2012

Extensions

a(0) = 1 prepended by Seiichi Manyama, Dec 09 2017

Status

approved