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 A034318 McKay-Thompson series of class 13A for the Monster group with a(0) = -2. 5
 1, -2, 12, 28, 66, 132, 258, 468, 843, 1428, 2406, 3900, 6253, 9780, 15144, 22980, 34599, 51300, 75430, 109584, 158052, 225676, 320082, 450216, 629329, 873444, 1205514, 1653364, 2256087, 3061620, 4135280, 5557980, 7438170, 9910132, 13151568, 17382756, 22891391 (list; graph; refs; listen; history; text; internal format)
 OFFSET -1,2 LINKS Vaclav Kotesovec, Table of n, a(n) for n = -1..5000 I. Chen and N. Yui, Singular values of Thompson series. In Groups, difference sets and the Monster (Columbus, OH, 1993), pp. 255-326, Ohio State University Mathematics Research Institute Publications, 4, de Gruyter, Berlin, 1996. J. H. Conway and S. P. Norton, Monstrous Moonshine, Bull. Lond. Math. Soc. 11 (1979) 308-339. D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994). FORMULA Expansion of Hauptmodul for Gamma_0(13)+. Expansion of (eta(q) / eta(q^13))^2 + 13*(eta(q^13) / eta(q))^2 in powers of q. - Michael Somos, Jul 05 2012 G.f.: (1/x) * Product_{k>0} ((1 - x^k) / (1 - x^(13*k)))^2 + 13*x * Product_{k>0} ((1 - x^(13*k)) / (1 - x^k))^2. - Michael Somos, Jul 05 2012 a(n) = A034319(n) unless n=0. - Michael Somos, Jul 05 2012 a(n) = A133099(n) + 13 * A121597(n). - Michael Somos, Jul 05 2012 a(n) ~ exp(4*Pi*sqrt(n/13)) / (sqrt(2) * 13^(1/4) * n^(3/4)). - Vaclav Kotesovec, Sep 08 2017 EXAMPLE G.f. = 1/q - 2 + 12*q + 28*q^2 + 66*q^3 + 132*q^4 + 258*q^5 + 468*q^6 + ... MATHEMATICA QP = QPochhammer; A = O[q]^40; A = (QP[q + A]/QP[q^13 + A])^2; s = A + 13*(q^2/A); CoefficientList[s, q] (* Jean-François Alcover, Nov 13 2015, adapted from PARI *) PROG (PARI) {a(n) = my(A); if( n<-1, 0, n++; A = x * O(x^n); A = (eta(x + A) / eta(x^13 + A))^2; polcoeff( A + 13 * x^2 / A, n))}; /* Michael Somos, Jul 05 2012 */ CROSSREFS Cf. A000521, A007240, A014708, A007241, A007267, A045478, etc. Cf. A034319, A121597, A133099. Sequence in context: A164876 A225291 A211623 * A248119 A240764 A215784 Adjacent sequences:  A034315 A034316 A034317 * A034319 A034320 A034321 KEYWORD sign,easy AUTHOR STATUS approved

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Last modified January 18 21:54 EST 2019. Contains 319282 sequences. (Running on oeis4.)