A321300 Expansion of Product_{1 <= i < j} (1 - x^(i*j)).

1, 0, -1, -1, -1, 0, -1, 1, 1, 2, 2, 2, 0, 0, 2, -2, -1, -3, -1, -4, -4, -4, -1, -1, -2, 0, 3, 7, 3, 4, 5, 7, 5, 8, 3, 2, 4, 1, -6, -2, -8, -8, -12, -9, -9, -11, -13, -12, -6, -8, -6, -8, 11, 5, 6, 8, 18, 12, 22, 21, 28, 26, 28, 12, 21, 22, 11, 0, 0, -4, -18, -17, -38

Offset: 0

Author

Seiichi Manyama, Nov 03 2018

Keywords

• sign
• look

Links

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

Crossrefs

Convolution inverse of A321285.

Cf. A056924, A321286, A321299.

Programs

Mathematica

nmax = 100; CoefficientList[Series[Product[(1 - x^k)^Floor[DivisorSigma[0, k]/2], {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 03 2018 *)

Formula

G.f.: Product_{k>0} (1 - x^k)^A056924(k).