OFFSET
-1,4
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 2 + (eta(q)*eta(q^5)/(eta(q^3)*eta(q^15)))^2 in powers of q. - G. C. Greubel, Jun 14 2018
EXAMPLE
T15B = 1/q - q + 4*q^2 - 3*q^3 - 2*q^4 + 11*q^5 - 6*q^6 - 11*q^7 + 20*q^8 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; b:= (eta[q]*eta[q^5]/(eta[q^3]* eta[q^15]))^2; a:= CoefficientList[Series[q*(2 + b), {q, 0, 60}], q]; Table[a[[n]], {n, 1, 50}] (* G. C. Greubel, Feb 13 2018 *)
PROG
(PARI) q='q+O('q^50); A = (eta(q)*eta(q^5)/(eta(q^3)*eta(q^15)))^2/q; Vec(2 + A) \\ G. C. Greubel, Jun 14 2018
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Nov 27 2000
EXTENSIONS
More terms from Michel Marcus, Feb 19 2014
STATUS
approved