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
Expansion of 3 + ((eta(q)*eta(q^6)*eta(q^10)*eta(q^15))/(eta(q^2) *eta(q^3)*eta(q^5)*eta(q^30)))^3 in powers of q. - G. C. Greubel, Jun 18 2018
a(n) ~ -(-1)^n * exp(2*Pi*sqrt(n/15)) / (2 * 15^(1/4) * n^(3/4)). - Vaclav Kotesovec, Jun 29 2018
EXAMPLE
T30A = 1/q + 3*q - q^2 - 3*q^6 + 9*q^7 - 9*q^8 + 3*q^9 - 3*q^10 + 9*q^11 - ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; A:= ((eta[q]*eta[q^6]*eta[q^10]* eta[q^15])/(eta[q^2]*eta[q^3]*eta[q^5]*eta[q^30]))^3; a:= CoefficientList[Series[3 + A, {q, 0, 60}], q]; Table[a[[n]], {n, 1, 50}] (* G. C. Greubel, Jun 18 2018 *)
PROG
(PARI) q='q+O('q^50); A = 3 + ((eta(q)*eta(q^6)*eta(q^10) *eta(q^15))/( eta(q^2)*eta(q^3)*eta(q^5)*eta(q^30)))^3/q; Vec(A) \\ G. C. Greubel, Jun 18 2018
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Nov 27 2000
EXTENSIONS
More terms from Michel Marcus, Feb 18 2014
STATUS
approved