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Theta series of direct sum of 2 copies of f.c.c. lattice.
1

%I #11 Jul 07 2017 17:22:55

%S 1,24,156,192,636,624,1312,1152,2556,1752,4056,2880,5152,4080,7872,

%T 4992,10236,6960,11388,8640,16536,9216,19680,12672,20512,15624,26520,

%U 15744,30912,20208,34112,23040

%N Theta series of direct sum of 2 copies of f.c.c. lattice.

%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 113.

%H <a href="/index/Fa#fcc">Index entries for sequences related to f.c.c. lattice</a>

%t terms = 32; s = 1/4 (EllipticTheta[3, 0, q]^3 + EllipticTheta[4, 0, q]^3)^2 + O[q]^(2 terms); CoefficientList[s, q^2] (* _Jean-François Alcover_, Jul 07 2017, from LatticeData(fcc) *)

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_.