A289346 Coefficients in expansion of E_6^(2/3).

1, -336, -39312, -8266944, -2529479568, -895678457184, -344891780549568, -140330667583849344, -59379605532142099344, -25873741825665005773200, -11534062764689844375098592, -5236325710480558290644292672

Offset: 0

Author

Seiichi Manyama, Jul 03 2017

Keywords

• sign

Crossrefs

E_6^(k/12): A109817 (k=1), A289325 (k=2), A289326 (k=3), A289327 (k=4), A289328 (k=5), A289293 (k=6), A289345 (k=7), this sequence (k=8), A289347 (k=9), A289348 (k=10), A289349 (k=11).

Cf. A013973 (E_6), A288851.

Programs

Mathematica

nmax = 20; CoefficientList[Series[(1 - 504*Sum[DivisorSigma[5,k]*x^k, {k, 1, nmax}])^(2/3), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)

Formula

G.f.: Product_{n>=1} (1-q^n)^(2*A288851(n)/3).

a(n) ~ c * exp(2*Pi*n) / n^(5/3), where c = -3^(1/3) * Gamma(1/4)^(32/3) / (128 * 2^(2/3) * Pi^8 * Gamma(1/3)) = -0.258650618394676269905172499217587002338... - Vaclav Kotesovec, Jul 08 2017, updated Mar 05 2018