A338730 Generating function Sum_{n >= 1} a(n)*x^n = Sum_{k>=1} k*x^(k*(3*k+1)/2)/(1-x^k).

0, 0, 1, 1, 1, 1, 1, 3, 1, 3, 1, 3, 1, 3, 1, 6, 1, 3, 4, 3, 1, 6, 1, 3, 4, 3, 5, 6, 1, 3, 8, 3, 1, 6, 5, 3, 4, 3, 5, 6, 6, 3, 8, 3, 1, 11, 5, 3, 4, 3, 10, 6, 1, 3, 8, 8, 1, 12, 5, 3, 9, 3, 5, 12, 1, 8, 8, 3, 1, 12, 10, 3, 4, 3, 5, 17, 1, 10, 8, 3, 6, 12, 5, 3, 11, 8, 5, 12, 1, 3

Offset: 0

Author

N. J. A. Sloane, Dec 02 2020

Keywords

• nonn

Comments

The OEIS contains many very similar sequences, but this one was missing.

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A001227, A081757, A117277, A330889, A338731, A338732.

Programs

PARI

my(N=66, x='x+O('x^N)); concat([0, 0], Vec(sum(k=1, N, k*x^(k*(3*k+1)/2)/(1-x^k)))) \\ Seiichi Manyama, Dec 03 2020