OFFSET
-1,3
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..1000
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).
J. McKay and H. Strauss, The q-series of monstrous moonshine and the decomposition of the head characters, Comm. Algebra 18 (1990), no. 1, 253-278.
FORMULA
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
EXAMPLE
T6D = 1/q - 2*q + 28*q^2 - 27*q^3 - 52*q^4 + 136*q^5 - 108*q^6 - 162*q^7 + ...
MATHEMATICA
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 *)
PROG
(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
CROSSREFS
KEYWORD
sign
AUTHOR
STATUS
approved