A289636 - OEIS

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A289636

Coefficients in expansion of -q*E'_4/E_4 where E_4 is the Eisenstein Series (A004009).

-240, 53280, -12288960, 2835808320, -654403831200, 151013228757120, -34848505552897920, 8041801037378486400, -1855762905734676483120, 428244362959801779806400, -98823634118413525094402880, 22804995243537595828606337280

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..422

FORMULA

a(n) = Sum_{d|n} d * A110163(d) = A289633(n)/6.

a(n) = A288261(n)/3 + 8*A000203(n).

a(n) = -Sum_{k=1..n-1} A004009(k)*a(n-k) - A004009(n)*n.

G.f.: 1/3 * E_6/E_4 - 1/3 * E_2.

a(n) ~ (-1)^n * exp(Pi*sqrt(3)*n). - Vaclav Kotesovec, Jul 09 2017

EXAMPLE

a(1) = 1 * A110163(1) = -240,

a(2) = 1 * A110163(1) + 2 * A110163(2) = 53280,

a(3) = 1 * A110163(1) + 3 * A110163(3) = -12288960.

MATHEMATICA

nmax = 20; Rest[CoefficientList[Series[-240*x*Sum[k*DivisorSigma[3, k]*x^(k-1), {k, 1, nmax}]/(1 + 240*Sum[DivisorSigma[3, k]*x^k, {k, 1, nmax}]), {x, 0, nmax}], x]] (* Vaclav Kotesovec, Jul 09 2017 *)

terms = 12; Ei[n_] = 1-(2n/BernoulliB[n]) Sum[k^(n-1) x^k/(1-x^k), {k, terms}]; CoefficientList[-D[Ei[4], x]/Ei[4] + O[x]^terms, x] (* Jean-François Alcover, Mar 01 2018 *)

CROSSREFS

-q*E'_k/E_k: A289635 (k=2), this sequence (k=4), A289637 (k=6), A289638 (k=8), A289639 (k=10), A289640 (k=14).

Cf. A001943, A004009 (E_4), A006352 (E_2), A110163, A145094, A289633.

Sequence in context: A258082 A269825 A232843 * A001943 A052263 A218514

Adjacent sequences: A289633 A289634 A289635 * A289637 A289638 A289639

KEYWORD

sign

AUTHOR

Seiichi Manyama, Jul 09 2017

STATUS

approved