A307757 Expansion of Product_{k>=1} 1/(1 + x^k/(1 + x^(2*k))).

1, -1, 0, 0, -1, 0, 2, -2, 0, 2, -2, 0, 4, -4, 0, 4, -5, 0, 8, -8, 0, 8, -10, 0, 14, -15, 0, 16, -18, 0, 24, -26, 0, 28, -32, 0, 42, -44, 0, 48, -54, 0, 68, -72, 0, 80, -88, 0, 108, -115, 0, 128, -140, 0, 170, -180, 0, 200, -218, 0, 260, -276, 0, 308, -333, 0, 392, -416, 0, 464

Offset: 0

Author

Seiichi Manyama, Sep 22 2019

Keywords

• sign

Crossrefs

Cf. A309733, A327686, A327688.

Programs

Mathematica

m = 70; CoefficientList[Series[Product[1/(1 + x^k/(1 + x^(2*k))), {k, 1, m}], {x, 0, m}], x] (* Amiram Eldar, May 07 2021 *)

PARI

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