A023911 - OEIS

%I #14 Jun 13 2019 04:13:57

%S 1,420,35910,1093260,15058680,113446872,579316080,2329395060,

%T 7731638460,22367855300,57613059966,136098325440,297252637920,

%U 612084784920,1190412837180,2219090508852,3958702871340,6845564237400,11427505500670,18625710365640,29498125917456

%N Theta series of A_20 lattice.

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

%t 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 *)

%K nonn

%O 0,2

%A _N. J. A. Sloane_

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

%E More terms from _Sean A. Irvine_, Jun 12 2019