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A023911 Theta series of A_20 lattice. 0
1, 420, 35910, 1093260, 15058680, 113446872, 579316080, 2329395060, 7731638460, 22367855300, 57613059966, 136098325440, 297252637920, 612084784920, 1190412837180, 2219090508852, 3958702871340, 6845564237400, 11427505500670, 18625710365640, 29498125917456 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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

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Last modified January 19 08:18 EST 2022. Contains 350464 sequences. (Running on oeis4.)