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 A058599 McKay-Thompson series of class 27A for the Monster group. 1
 1, 0, 3, 5, 9, 12, 20, 27, 42, 57, 81, 108, 150, 198, 267, 346, 459, 588, 765, 972, 1248, 1570, 1989, 2484, 3117, 3861, 4800, 5908, 7290, 8916, 10922, 13284, 16170, 19565, 23679, 28512, 34331, 41148, 49308, 58854, 70218, 83484, 99193, 117504, 139092 (list; graph; refs; listen; history; text; internal format)
 OFFSET -1,3 COMMENTS Also McKay-Thompson series of class 27B for the Monster group. LINKS Vaclav Kotesovec, Table of n, a(n) for n = -1..10000 (terms -1..1000 from G. C. Greubel) D. Ford, J. McKay and S. P. Norton, More on replicable functions, Comm. Algebra 22, No. 13, 5175-5193 (1994). FORMULA Expansion of T9B(q)/(1 - 3*T9B(q)/(6 + T9B(q^3))), where T9B(q) = A058091 and T9B(q^3) = T9B(q -> q^3), in powers of q. - G. C. Greubel, Jun 22 2018 a(n) ~ exp(4*Pi*sqrt(n/3)/3) / (sqrt(2) * 3^(3/4) * n^(3/4)). - Vaclav Kotesovec, Jun 28 2018 EXAMPLE T27A = 1/q +3*q +5*q^2 +9*q^3 +12*q^4 +20*q^5 +27*q^6 +42*q^7 +... MATHEMATICA eta[q_]:= q^(1/24)*QPochhammer[q]; nmax := 100;  B:= (eta[q^6]/eta[q^3])*(eta[q^9]/eta[q^18])^3;  T9B := B + 4/(B)^2; A:= T9B/(6 + (T9B/.{q -> q^3})) ;  a:= CoefficientList[Series[q*T9B/(1 - 3*A + O[q]^nmax), {q, 0, 60}], q]; Table[a[[n]], {n, 1, 50}] (* G. C. Greubel, Jun 22 2018 *) PROG (PARI) q='q+O('q^50); B = (eta(q^6)/eta(q^3))*(eta(q^9)/eta(q^18))^3/q; B3 = (eta(q^18)/eta(q^9))*(eta(q^27)/eta(q^54))^3/q^3; T9B = B + 4/B^2; T9B3 = B3 + 4/(B3)^2; A = T9B/(6 + T9B3); Vec(T9B/(1 - 3*A)) \\ G. C. Greubel, Jun 22 2018 CROSSREFS Cf. A000521, A007240, A014708, A007241, A007267, A045478, etc. Sequence in context: A265702 A190310 A046746 * A238662 A059093 A084593 Adjacent sequences:  A058596 A058597 A058598 * A058600 A058601 A058602 KEYWORD nonn AUTHOR N. J. A. Sloane, Nov 27 2000 STATUS approved

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Last modified January 22 05:11 EST 2019. Contains 319353 sequences. (Running on oeis4.)