OFFSET
-1,7
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, Comm. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
Expansion of B + q/B, where B = q^(1/2)*(eta(q)*eta(q^6)*eta(q^14)* eta(q^21)/(eta(q^2)*eta(q^3)*eta(q^7)*eta(q^42))), in powers of q. - G. C. Greubel, Jun 30 2018
a(n) ~ exp(2*Pi*sqrt(n/21)) / (2 * 21^(1/4) * n^(3/4)). - Vaclav Kotesovec, Jul 02 2018
EXAMPLE
T84A = 1/q + q^3 + q^5 + q^7 + 3*q^11 + 2*q^13 + 2*q^15 + 2*q^17 + 2*q^19 + ...
MATHEMATICA
eta[q_] := q^(1/24)*QPochhammer[q]; B:= q^(1/2)*(eta[q]*eta[q^6]* eta[q^14]*eta[q^21]/(eta[q^2]*eta[q^3]*eta[q^7]*eta[q^42])); a:= CoefficientList[Series[B + q/B , {q, 0, 60}], q]; Table[a[[n]], {n, 0, 50}] (* G. C. Greubel, Jun 30 2018 *)
PROG
(PARI) q='q+O('q^50); B = (eta(q)*eta(q^6)*eta(q^14)*eta(q^21)/( eta(q^2) *eta(q^3)*eta(q^7)*eta(q^42))); Vec(B + q/B) \\ G. C. Greubel, Jun 30 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 27 2000
EXTENSIONS
Terms a(12) onward added by G. C. Greubel, Jun 30 2018
STATUS
approved