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%I #15 Jun 27 2018 10:27:21
%S 1,0,3,4,9,12,15,24,39,52,66,96,130,168,219,292,390,492,625,804,1023,
%T 1280,1599,2016,2508,3096,3807,4688,5760,7020,8532,10368,12585,15156,
%U 18213,21912,26287,31404,37410,44584,53004,62784,74245,87768,103578
%N McKay-Thompson series of class 28B for the Monster group.
%H G. C. Greubel, <a href="/A112169/b112169.txt">Table of n, a(n) for n = -1..1500</a>
%H D. Ford, J. McKay and S. P. Norton, <a href="http://dx.doi.org/10.1080/00927879408825127">More on replicable functions</a>, Commun. Algebra 22, No. 13, 5175-5193 (1994).
%H <a href="/index/Mat#McKay_Thompson">Index entries for McKay-Thompson series for Monster simple group</a>
%F Expansion of A + 1 + 4/A, where A = eta(q)*eta(q^7)/(eta(q^4)*eta(q^28)), in powers of q. - _G. C. Greubel_, Jun 25 2018
%F a(n) ~ exp(2*Pi*sqrt(n/7)) / (2 * 7^(1/4) * n^(3/4)). - _Vaclav Kotesovec_, Jun 27 2018
%e T28B = 1/q + 3*q + 4*q^2 + 9*q^3 + 12*q^4 + 15*q^5 + 24*q^6 + 39*q^7 + ...
%t eta[q_]:= q^(1/24)*QPochhammer[q]; A:= (eta[q]*eta[q^7]/(eta[q^4]* eta[q^28])); a:= CoefficientList[Series[q*(1 + A + 4/A), {q, 0, 60}], q]; Table[a[[n]], {n, 1, 1502}] (* _G. C. Greubel_, Jun 25 2018 *)
%o (PARI) q='q+O('q^50); A = eta(q)*eta(q^7)/(q*eta(q^4)*eta(q^28)); Vec(A + 1 + 4/A) \\ _G. C. Greubel_, Jun 25 2018
%K nonn
%O -1,3
%A _Michael Somos_, Aug 28 2005
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