A023911 Theta series of A_20 lattice.

1, 420, 35910, 1093260, 15058680, 113446872, 579316080, 2329395060, 7731638460, 22367855300, 57613059966, 136098325440, 297252637920, 612084784920, 1190412837180, 2219090508852, 3958702871340, 6845564237400, 11427505500670, 18625710365640, 29498125917456

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..20.

Mathematica

terms = 17; f[q_] = LatticeData["A20", "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: A022046 A289348 A107510 * A135340 A135380 A035846

Adjacent sequences: A023908 A023909 A023910 * A023912 A023913 A023914

Keyword

nonn

Author

N. J. A. Sloane

Extensions

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

More terms from Sean A. Irvine, Jun 12 2019

Status

approved