OFFSET
0,2
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 118.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
Expansion of 1/2 (EllipticTheta(3, 0, q)^9 + EllipticTheta(4, 0, q)^9) (formula given by Mathematica's LatticeData(D9)). - Jean-François Alcover, Jul 07 2017
MATHEMATICA
terms = 24; s = 1/2 (EllipticTheta[3, 0, q]^9 + EllipticTheta[4, 0, q]^9) + O[q]^(2 terms); CoefficientList[s, q^2] (* Jean-François Alcover, Jul 07 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Seiichi Manyama, Oct 16 2018
STATUS
approved