OFFSET
-1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..1500
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
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
a(n) ~ exp(2*Pi*sqrt(n/7)) / (2 * 7^(1/4) * n^(3/4)). - Vaclav Kotesovec, Jun 27 2018
EXAMPLE
T28B = 1/q + 3*q + 4*q^2 + 9*q^3 + 12*q^4 + 15*q^5 + 24*q^6 + 39*q^7 + ...
MATHEMATICA
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 *)
PROG
(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
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Aug 28 2005
STATUS
approved