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 A289635 Coefficients in expansion of -q*E'_2/E_2 where E_2 is the Eisenstein Series (A006352). 7
 24, 720, 19296, 517920, 13893264, 372707136, 9998360256, 268219317312, 7195339794744, 193024557070560, 5178140391612960, 138910500937231488, 3726458885094926160, 99967214347459657344, 2681753442755678231616 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Seiichi Manyama, Table of n, a(n) for n = 1..700 FORMULA a(n) = Sum_{d|n} d * A288968(d). a(n) = A288877(n)/12 + 2*A000203(n). a(n) = -Sum_{k=1..n-1} A006352(k)*a(n-k) - A006352(n)*n. G.f.: 1/12 * E_4/E_2 - 1/12 * E_2. a(n) ~ 1 / r^n, where r = A211342 = 0.037276810296451658150980785651644618... is the root of the equation Sum_{k>=1} A000203(k) * r^k = 1/24. - Vaclav Kotesovec, Jul 09 2017 EXAMPLE a(1) = - A006352(1)*1 = 24, a(2) = -(A006352(1)*a(1)) - A006352(2)*2 = 720, a(3) = -(A006352(1)*a(2)  + A006352(2)*a(1)) - A006352(3)*3 = 19296, a(4) = -(A006352(1)*a(3)  + A006352(2)*a(2)  + A006352(3)*a(1)) - A006352(4)*4 = 517920. MATHEMATICA nmax = 20; Rest[CoefficientList[Series[24*x*Sum[k*DivisorSigma[1, k]*x^(k-1), {k, 1, nmax}]/(1 - 24*Sum[DivisorSigma[1, k]*x^k, {k, 1, nmax}]), {x, 0, nmax}], x]] (* Vaclav Kotesovec, Jul 09 2017 *) CROSSREFS -q*E'_k/E_k: this sequence (k=2), A289636 (k=4), A289637 (k=6), A289638 (k=8), A289639 (k=10), A289640 (k=14). Cf. A000203, A006352 (E_2), A076835, A211342, A288816, A288877, A288968. Sequence in context: A189412 A246192 A246612 * A105187 A062313 A239815 Adjacent sequences:  A289632 A289633 A289634 * A289636 A289637 A289638 KEYWORD nonn AUTHOR Seiichi Manyama, Jul 09 2017 STATUS approved

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Last modified January 24 19:03 EST 2022. Contains 350565 sequences. (Running on oeis4.)