%I #12 Jul 06 2017 08:56:16
%S 1,0,0,16,12,0,64,96,60,0,0,240,160,0,384,416,252,0,0,720,312,0,960,
%T 1056,544,0,0,1312,960,0,1664,1920,1020,0,0,2496,876,0,2880,2720,1560,
%U 0,0,3696,2400,0,4224,4416
%N Theta series of direct sum of 2 copies of b.c.c. lattice.
%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", SpringerVerlag, p. 116.
%H <a href="/index/Ba#bcc">Index entries for sequences related to b.c.c. lattice</a>
%F G.f.: (theta_3(z)*theta_3(z)*theta_3(z)+theta_2(z)*theta_2(z)*theta_2(z))^2.
%t terms = 48; t2 = EllipticTheta[2, 0, z]; t3 = EllipticTheta[3, 0, z]; s = Normal[(t3^3 + t2^3)^2 + O[z]^terms] /. z > z^4 // Simplify[#, z > 0]&; CoefficientList[s, z][[1 ;; terms]] (* _JeanFrançois Alcover_, Jul 06 2017 *)
%K nonn,easy
%O 0,4
%A _N. J. A. Sloane_.
