cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A145094 Coefficients in expansion of Eisenstein series q*E'_4.

Original entry on oeis.org

240, 4320, 20160, 70080, 151200, 362880, 577920, 1123200, 1635120, 2721600, 3516480, 5886720, 6857760, 10402560, 12700800, 17975040, 20049120, 29432160, 31281600, 44150400, 48545280, 63296640, 67167360, 94348800, 94506000, 123439680, 132451200
Offset: 1

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Author

N. J. A. Sloane, Feb 28 2009

Keywords

Examples

			G.f. = 240*q + 4320*q^2 + 20160*q^3 + 70080*q^4 + 151200*q^5 + ...
		

Crossrefs

Cf. A076835 (-q*E'_2), this sequence (q*E'_4), A145095 (-q*E'_6).

Programs

  • Mathematica
    terms = 28;
    E2[x_] = 1 - 24*Sum[k*x^k/(1 - x^k), {k, 1, terms}];
    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}];
    (E2[x]*E4[x] - E6[x])/3 + O[x]^terms // CoefficientList[#, x]& // Rest (* Jean-François Alcover, Feb 23 2018 *)
    nmax = 40; Rest[CoefficientList[Series[240*x*Sum[k^4*x^(k-1)/(1 - x^k)^2, {k, 1, nmax}], {x, 0, nmax}], x]] (* Vaclav Kotesovec, Aug 01 2025 *)

Formula

q*E'_4 = (E_2*E_4-E_6)/3.
G.f.: 240*x*f'(x), where f(x) = Sum_{k>=1} k^3*x^k/(1 - x^k). - Ilya Gutkovskiy, Aug 31 2017
Sum_{k=1..n} a(k) ~ 8 * Pi^4 * n^5 / 15. - Vaclav Kotesovec, May 09 2022