A022052 Theta series of D_21 lattice.

1, 840, 95802, 3504816, 55350120, 465944304, 2610853840, 11337146784, 40208417466, 123411903160, 335056780464, 830096613360, 1893781702512, 4058779021584, 8190877926720, 15805879161632, 29122237029480, 51905458442208, 89163973663338, 149313692762640, 242598110651568

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

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..1000

Programs

Mathematica

terms = 17; f[q_] = LatticeData["D21", "ThetaSeriesFunction"][-I*Log[q]/Pi]; s = f[q] + O[q]^(2 terms); DeleteCases[CoefficientList[s, q], 0][[1 ;; terms]] (* Jean-François Alcover, Jul 06 2017 *)

Extensions

More terms from Seiichi Manyama, Oct 16 2018