OFFSET
-1,4
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..2500
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
Expansion of 2 + (eta(q)*eta(q^4)*eta(q^10)/(eta(q^2)*eta(q^5) *eta(q^20)))^2 in powers of q. - G. C. Greubel, Jun 06 2018
EXAMPLE
T20C = 1/q + q - 2*q^2 + 2*q^3 + 2*q^4 - q^5 - 4*q^7 + 2*q^8 + 5*q^9 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; a:= CoefficientList[Series[q*(2 + (eta[q]*eta[q^4]*eta[q^10]/(eta[q^2]*eta[q^5]*eta[q^20]))^2), {q, 0, 60}], q]; Table[a[[n]], {n, 1, 50}] (* G. C. Greubel, Jun 06 2018 *)
PROG
(PARI) q='q+O('q^80); F = 2 + (eta(q)*eta(q^4)*eta(q^10)/(eta(q^2) *eta(q^5)*eta(q^20)))^2/q; Vec(F) \\ G. C. Greubel, Jun 06 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Michael Somos, Aug 28 2005
STATUS
approved