A299861 Coefficients in expansion of (E_6^2/E_4^3)^(1/4).

1, -432, 41472, -19704384, 593104896, -1488746462112, -215673487239168, -180545262418802304, -58940991594820435968, -31030127172303490499184, -13143520096697989968012288, -6336110261914309914844683456

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..367

Formula

G.f.: (1 - 1728/j)^(1/4), where j is the j-function.

a(n) ~ -3^(1/4) * Gamma(1/4)^2 * exp(2*Pi*n) / (8 * Pi^2 * n^(3/2)). - Vaclav Kotesovec, Mar 04 2018

a(n) * A300053(n) ~ -exp(4*Pi*n) / (2*Pi*n^2). - Vaclav Kotesovec, Mar 04 2018

Mathematica

terms = 12;
E4[x_] = 1 + 240*Sum[k^3*x^k/(1 - x^k), {k, 1, terms}];
E6[x_] = 1 - 504*Sum[k^5*x^k/(1 - x^k), {k, 1, terms}];
(E6[x]^2/E4[x]^3)^(1/4) + O[x]^terms // CoefficientList[#, x]& (* Jean-François Alcover, Feb 28 2018 *)

Crossrefs

(E_6^2/E_4^3)^(k/288): A289366 (k=1), A296609 (k=2), A296614 (k=3), A296652 (k=4), A297021 (k=6), A299422 (k=8), A299862 (k=9), A289368 (k=12), A299856 (k=16), A299857 (k=18), A299858 (k=24), A299863 (k=32), A299859 (k=36), A299860 (k=48), this sequence (k=72), A299414 (k=96), A299413 (k=144), A289210 (k=288).

Cf. A000521 (j), A289334, A299830.

Sequence in context: A282752 A290180 A281986 * A269149 A113921 A269211

Adjacent sequences: A299858 A299859 A299860 * A299862 A299863 A299864

Keyword

sign

Author

Seiichi Manyama, Feb 21 2018

Status

approved