OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
a(n) ~ exp(sqrt(2*n/5)*Pi) / (2^(5/4) * 5^(1/4) * n^(3/4)). - Vaclav Kotesovec, Apr 30 2017
Expansion of q^(1/2)*((eta(q^2)*eta(q^10))^2/(eta(q)*eta(q^4)*eta(q^5) *eta(q^20)))^2 in powers of q. - G. C. Greubel, Feb 13 2018
EXAMPLE
T40B = 1/q +2*q +q^3 +2*q^5 +4*q^7 +6*q^9 +9*q^11 +8*q^13 +...
MATHEMATICA
nmax = 60; CoefficientList[Series[Product[((1 + x^(2*k-1))/((1 + x^(10*k))*(1 - x^(10*k-5))))^2, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 30 2017 *)
eta[q_] := q^(1/24)*QPochhammer[q]; e40B:= q^(1/2)*((eta[q^2]*eta[q^10] )^2/(eta[q]*eta[q^4]*eta[q^5]*eta[q^20]))^2; Table[ SeriesCoefficient[ e40B, {q, 0, n}], {n, 0, 50}] (* G. C. Greubel, Feb 13 2018 *)
PROG
(PARI) q='q+O('q^50); A = ((eta(q^2)*eta(q^10))^2/(eta(q)*eta(q^4)* eta(q^5)*eta(q^20)))^2; Vec(A) \\ G. C. Greubel, Jun 16 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Aug 28 2005
STATUS
approved