OFFSET
-1,2
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
Expansion of A + q/A, where A = q^(1/2)*((eta(q^2)*eta(q^7))/(eta(q) *eta(q^14)))^2, in powers of q. - G. C. Greubel, Jun 18 2018
a(n) ~ exp(2*Pi*sqrt(n/7)) / (2 * 7^(1/4) * n^(3/4)). - Vaclav Kotesovec, Jun 28 2018
EXAMPLE
T28A = 1/q + 3*q + q^3 + 7*q^5 + 7*q^7 + 18*q^9 + 18*q^11 + 35*q^13 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; e28D:= q^(1/2)*((eta[q^2]*eta[q^7])/(eta[q]*eta[q^14]))^2; a[n_]:= SeriesCoefficient[e28D + q/e28D, {q, 0, n}]; Table[a[n], {n, 0, 50}] (* G. C. Greubel, Feb 18 2018 *)
PROG
(PARI) q='q+O('q^50); A = ((eta(q^2)*eta(q^7))/(eta(q) *eta(q^14)))^2; Vec(A + q/A) \\ G. C. Greubel, Jun 18 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 27 2000
EXTENSIONS
Terms a(12) onward added by G. C. Greubel, Feb 18 2018
STATUS
approved