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%I #12 Oct 16 2018 12:00:00
%S 1,840,95802,3504816,55350120,465944304,2610853840,11337146784,
%T 40208417466,123411903160,335056780464,830096613360,1893781702512,
%U 4058779021584,8190877926720,15805879161632,29122237029480,51905458442208,89163973663338,149313692762640,242598110651568
%N Theta series of D_21 lattice.
%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 118.
%H Seiichi Manyama, <a href="/A022052/b022052.txt">Table of n, a(n) for n = 0..1000</a>
%t terms = 17; f[q_] = LatticeData["D21", "ThetaSeriesFunction"][-I*Log[q]/Pi]; s = f[q] + O[q]^(2 terms); DeleteCases[CoefficientList[s, q], 0][[1 ;; terms]] (* _Jean-François Alcover_, Jul 06 2017 *)
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_
%E More terms from _Seiichi Manyama_, Oct 16 2018