OFFSET
0,2
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 407.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
This series is the q-expansion of (7*E_4(z)^3 + 2*E_6(z)^2)/9. - Daniel D. Briggs, Nov 25 2011
MATHEMATICA
terms = 15; th = EllipticTheta; E4 = 1 + 240*Sum[k^3*(q^k/(1 - q^k)), {k, 1, terms}] + O[q]^terms; E6 = th[2, 0, q]^12 + th[3, 0, q]^12 - 33*th[2, 0, q]^4*th[3, 0, q]^4*(th[2, 0, q]^4 + th[3, 0, q]^4); CoefficientList[(7/9)*E4^3 + (2/9)*E6^2 + O[q]^terms, q] (* Jean-François Alcover, Jul 05 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved