A038069 Product_{k>=1} ((1 + x^k)^a(k)) = 1 + 4x.

4, -6, 20, -66, 204, -670, 2340, -8226, 29120, -104754, 381300, -1398410, 5162220, -19172790, 71582716, -268439586, 1010580540, -3817733920, 14467258260, -54975633702, 209430785460, -799644629550, 3059510616420

Offset: 1

Author

Christian G. Bower, Jan 04 1999

Keywords

• sign

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..1000
• N. J. A. Sloane, Weigh transform

Crossrefs

Cf. A038063-A038070, A306158.

Formula

Dirichlet convolution of A038065 with characteristic function of powers of 2.

a(n) = (1/n)*(-(-4)^n + Sum_{dSeiichi Manyama, Jun 23 2018