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%I #11 Oct 23 2018 07:11:05
%S 1,21,399,6783,102249,1370565,16991415,216411615,3146775345,
%T 49819225365,767467173375,11808542505375,208290421179225,
%U 4084751136190725,76593243172220775,1426967042034909375
%N Expansion of e.g.f. theta_3^(21/2).
%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 102.
%H Seiichi Manyama, <a href="/A015677/b015677.txt">Table of n, a(n) for n = 0..445</a>
%t nmax = 25; CoefficientList[Series[EllipticTheta[3, 0, x]^(21/2), {x, 0, nmax}], x] * Range[0, nmax]! (* _Vaclav Kotesovec_, Oct 23 2018 *)
%K nonn
%O 0,2
%A _N. J. A. Sloane_