OFFSET
-1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..1000
J. H. Conway and S. P. Norton, Monstrous Moonshine, Bull. Lond. Math. Soc. 11 (1979) 308-339.
N. D. Elkies, Elliptic and modular curves over finite fields and related computational issues, in AMS/IP Studies in Advanced Math., 7 (1998), 21-76, esp. p. 39.
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Commun. Algebra 22, No. 13, 5175-5193 (1994).
J. McKay and H. Strauss, The q-series of monstrous moonshine and the decomposition of the head characters, Comm. Algebra 18 (1990), no. 1, 253-278.
FORMULA
Expansion of (eta(q) / eta(q^7))^4 + 4 in powers of q.
EXAMPLE
T7B = 1/q + 2*q + 8*q^2 - 5*q^3 - 4*q^4 - 10*q^5 + 12*q^6 - 7*q^7 + 8*q^8 + ...
MATHEMATICA
QP = QPochhammer; s = (QP[q]/QP[q^7])^4 + 4*q + O[q]^50; CoefficientList[s, q] (* Jean-François Alcover, Nov 15 2015 *)
PROG
(PARI) q='q+O('q^30); Vec(4*q + (eta(q)/eta(q^7))^4) \\ G. C. Greubel, May 05 2018
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Nov 25 2000
STATUS
approved