A023909 - OEIS

%I #11 Jun 12 2019 20:55:11

%S 1,342,23256,548454,5756202,33953760,145404264,501480756,1455087222,

%T 3744992834,8666394912,18652602708,37257431778,70992509796,

%U 127919023344,222954244860,372270931974,606984681420,955026275808,1477806578172,2218909983696,3290673763164

%N Theta series of A_18 lattice.

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

%t terms = 18; f[q_] = LatticeData["A18", "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