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%I #13 Sep 08 2022 08:44:35
%S 1,56,420,896,2366,3360,6440,7168,14196,14168,22120,24192,37912,33824,
%T 55440,50176,75838,71232,98700,88704,141960,117824,156520,150528,
%U 217672,173656,261240,218624,303424,273504,355600,301056,455028,359744,474320
%N Theta series of A_7 lattice.
%D J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 110.
%t terms = 29; f[q_] = LatticeData["A7", "ThetaSeriesFunction"][-I Log[q]/Pi]; s = Series[f[q], {q, 0, 2 terms}]; DeleteCases[CoefficientList[s, q^(1/2) ] // Round, 0][[1 ;; terms]] (* _Jean-François Alcover_, Jul 04 2017 *)
%o (Magma) L:=Lattice("A",7); T1<q> := ThetaSeries(L,60);
%Y Cf. A023919 (dual).
%K nonn
%O 0,2
%A _N. J. A. Sloane_.
%E More terms from _Sean A. Irvine_, Jun 12 2019
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