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%I M2147 #22 Jun 02 2018 21:27:24
%S 1,0,-2,28,-27,-52,136,-108,-162,620,-486,-760,1970,-1404,-1940,6048,
%T -4293,-6100,15796,-10692,-14264,40232,-27108,-36496,93285,-61020,
%U -79054,211624,-137781,-179296,451680,-288360,-365780
%N McKay-Thompson series of class 6D for Monster.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H G. C. Greubel, <a href="/A007257/b007257.txt">Table of n, a(n) for n = -1..1000</a>
%H J. H. Conway and S. P. Norton, <a href="http://blms.oxfordjournals.org/content/11/3/308.extract">Monstrous Moonshine</a>, Bull. Lond. Math. Soc. 11 (1979) 308-339.
%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 J. McKay and H. Strauss, <a href="http://dx.doi.org/10.1080/00927879008823911">The q-series of monstrous moonshine and the decomposition of the head characters</a>, Comm. Algebra 18 (1990), no. 1, 253-278.
%H <a href="/index/Mat#McKay_Thompson">Index entries for McKay-Thompson series for Monster simple group</a>
%F Expansion of 4 + (eta(q)*eta(q^2)/(eta(q^3)*eta(q^6)))^4 in powers of q. - _G. C. Greubel_, Jan 30 2018
%e T6D = 1/q - 2*q + 28*q^2 - 27*q^3 - 52*q^4 + 136*q^5 - 108*q^6 - 162*q^7 + ...
%t eta[q_] := q^(1/24)*QPochhammer[q]; a[n_]:= SeriesCoefficient[4 + (eta[q] *eta[q^2]/(eta[q^3]*eta[q^6]))^4, {q, 0, n}]; Table[a[n], {n, -1, 50}] (* _G. C. Greubel_, Jan 30 2018 *)
%o (PARI) q='q+O('q^30); a= 4 + (eta(q)*eta(q^2)/(eta(q^3)*eta(q^6)))^4/q; Vec(a) \\ _G. C. Greubel_, Jun 02 2018
%Y Cf. A045487.
%K sign
%O -1,3
%A _N. J. A. Sloane_
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