OFFSET
-1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..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(2*Pi*sqrt(2*n/13)) / (2^(3/4) * 13^(1/4) * n^(3/4)). - Vaclav Kotesovec, Sep 08 2017
Expansion of -2 + ((eta(q^2)*eta(q^13))/(eta(q)* eta(q^26)))^2 in powers of q. - G. C. Greubel, Feb 18 2018
EXAMPLE
T26B = 1/q + 3*q + 6*q^2 + 9*q^3 + 14*q^4 + 22*q^5 + 32*q^6 + 46*q^7 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; e26B:= ((eta[q^2]*eta[q^13])/(eta[q]* eta[q^26]))^2; Table[SeriesCoefficient[-2 + e26B, {q, 0, n}], {n, -1, 50}] (* G. C. Greubel, Feb 18 2018 *)
PROG
(PARI) q='q+O('q^50); A = -2 + ((eta(q^2)*eta(q^13))/(eta(q)*eta(q^26)) )^2/q; Vec(A) \\ G. C. Greubel, Jun 14 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 27 2000
EXTENSIONS
More terms from Michel Marcus, Feb 18 2014
STATUS
approved