OFFSET
0,4
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 195.
LINKS
Andy Huchala, Table of n, a(n) for n = 0..20000
FORMULA
G.f.: E4(q)^8 - 1920 * E4(q)^5 * Delta(q) + 627840 * E4(q)^2 * Delta(q)^2 with E4(q) as in A004009 and Delta(q) as in A000594. - Andy Huchala, Jun 04 2021
EXAMPLE
G.f.: 1 + 2611200*q^3 + 19524758400*q^4 + ...
PROG
(Sage)
e4 = eisenstein_series_qexp(4, 20, normalization = "integral");
delta = CuspForms(1, 12).0.q_expansion(20);
e4^8 - 1920*e4^5*delta + 627840*e4^2*delta^2 # Andy Huchala, Jun 04 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved