A022073 - OEIS

%I #8 Jul 15 2021 01:46:04

%S 1,40,760,9120,77560,1546224,2508000,31204160,34729720,300136200,

%T 259114704,1823305440,1327461600,8216920880,5341699520,29758804416,

%U 17701924600,91800254160,51294999960,249835104800,131880275664,614963569920,312126610080,1394448792000

%N Theta series of D*_20 lattice.

%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 120.

%H Andy Huchala, <a href="/A022073/b022073.txt">Table of n, a(n) for n = 0..20000</a>

%e G.f. = 1 + 40*q^2 + 760*q^4 + ...

%o (Sage)

%o L = [ 1, 40, 760]

%o M = ModularForms(Gamma0(2),10)

%o bases = [_.q_expansion(20) for _ in M.integral_basis()]

%o f = sum(x*y for (x,y) in zip(bases,L)); list(f) # _Andy Huchala_, Jul 14 2021

%K nonn

%O 0,2

%A _N. J. A. Sloane_

%E More terms from _Andy Huchala_, Jul 14 2021