A327718 Expansion of Product_{k>=1} (1 + x^k/(1 + x^(2*k)/(1 + x^(3*k)))).

1, 1, 1, 1, 2, 3, 3, 3, 4, 6, 8, 9, 9, 11, 15, 20, 21, 20, 24, 36, 48, 46, 41, 52, 80, 100, 88, 74, 103, 170, 207, 166, 124, 198, 354, 409, 269, 162, 369, 745, 802, 382, 136, 706, 1585, 1515, 328, -178, 1422, 3481, 2822, -387, -1283, 3144, 7816, 4951, -3451, -4472, 7694, 18055

Offset: 0

Author

Seiichi Manyama, Sep 23 2019

Keywords

• sign
• look

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..1000

Crossrefs

Convolution inverse of A327686.

Cf. A327716, A327717, A327719, A327720.

Programs

Mathematica

nmax = 60; CoefficientList[Series[Product[(1 - x^(5*k)) / ((1 - x^k)*(1 + x^(2*k) + x^(3*k))), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 23 2019 *)

PARI

N=66; x='x+O('x^N); Vec(prod(k=1, N, 1+x^k/(1+x^(2*k)/(1+x^(3*k)))))