A023912 Theta series of A_21 lattice.

1, 462, 43890, 1501500, 23437722, 198944592, 1114627514, 4828206900, 17160463320, 52574485502, 143000133276, 353652649308, 808266398940, 1728870130680, 3496186881264, 6732994928660, 12429951473478

Offset

0,2

References

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 110.

Links

Table of n, a(n) for n=0..16.

Mathematica

terms = 17; f[q_] = LatticeData["A21", "ThetaSeriesFunction"][-I*Log[q]/Pi]; s = f[q] + O[q]^(2 terms); Partition[CoefficientList[s, q] // Round, 2][[All, 1]][[1 ;; terms]] (* Jean-François Alcover, Jul 06 2017 *)

Crossrefs

Sequence in context: A194718 A267283 A289349 * A027565 A035847 A140905

Adjacent sequences: A023909 A023910 A023911 * A023913 A023914 A023915

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Robert.Harley(AT)inria.fr, see A023902.

Status

approved