A308291 Expansion of Sum_{k>=1} mu(k)*log(1 + x^k/(1 - x^k)^4)/k.

1, 3, 6, 4, -3, -22, -23, 8, 88, 139, -19, -472, -869, -101, 2684, 5668, 2104, -15300, -37680, -22428, 86645, 252383, 202936, -482512, -1694944, -1710607, 2584008, 11368664, 13819803, -12802724, -75911328, -108463344, 53647377, 503132556, 833364427, -127320060

Offset: 1

Author

Ilya Gutkovskiy, May 18 2019

Keywords

• sign

Comments

Inverse Euler transform of tetrahedral numbers (A000292).

Crossrefs

Cf. A000292, A000335, A008683, A308290.

Programs

Mathematica

nmax = 36; CoefficientList[Series[Sum[MoebiusMu[k] Log[1 + x^k/(1 - x^k)^4]/k, {k, 1, nmax}], {x, 0, nmax}], x] // Rest
nmax = 50; s = ConstantArray[0, nmax]; Do[s[[j]] = j^2*(j + 1)*(j + 2)/6 - Sum[s[[d]]*(j - d)*(j - d + 1)*(j - d + 2)/6, {d, 1, j - 1}], {j, 1, nmax}]; Table[Sum[MoebiusMu[k/d]*s[[d]], {d, Divisors[k]}]/k, {k, 1, nmax}] (* Vaclav Kotesovec, Aug 10 2019 *)

Formula

-1 + Product_{n>=1} 1/(1 - x^n)^a(n) = g.f. of A000292.