A008431 Theta series of D_9 lattice.

1, 144, 2034, 7392, 22608, 44640, 93984, 141120, 262386, 343536, 557280, 703584, 1068384, 1234080, 1851264, 2057280, 2884176, 3231936, 4428242, 4639392, 6455520, 6670272, 8814816, 9320256, 12065568, 12152880, 16161120, 16124544, 20496960, 20906208, 26378880, 25736832

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

Sequence in context: A356731 A368508 A066445 * A250084 A280025 A223687

Adjacent sequences: A008428 A008429 A008430 * A008432 A008433 A008434

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from Seiichi Manyama, Oct 16 2018

Status

approved