OFFSET
-1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = -1..1002
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, Comm. 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
a(n) ~ exp(4*Pi*sqrt(n/3)) / (sqrt(2) * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, Apr 01 2017
MATHEMATICA
QP = QPochhammer; A = q*O[q]^20; A = (QP[q^3 + A]/QP[q + A])^12; s = (1 + 27*q*A)^2/A - 36*q; CoefficientList[s, q] (* Jean-François Alcover, Mar 08 2017, after Michael Somos (A007243) *)
CROSSREFS
KEYWORD
nonn,nice,easy
AUTHOR
STATUS
approved