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%I #16 Sep 06 2023 01:59:55
%S 1,702,123552,9746802,438575202,12873059082,268708978512,
%T 4237937201862,52823066222862,538709704223262,4620645082106352,
%U 34084184942296242,220231986648034842,1265712901796074842,6554224549952044992
%N Coordination sequence for A_26 lattice.
%H R. Bacher, P. de la Harpe and B. Venkov, <a href="http://dx.doi.org/10.1016/S0764-4442(97)83542-2">Séries de croissance et séries d'Ehrhart associées aux réseaux de racines</a>, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.
%H J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (<a href="http://neilsloane.com/doc/Me220.pdf">pdf</a>).
%H Joan Serra-Sagrista, <a href="http://dx.doi.org/10.1016/S0020-0190(00)00119-8">Enumeration of lattice points in l_1 norm</a>, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
%H <a href="/index/Rec#order_26">Index entries for linear recurrences with constant coefficients</a>, signature (26, -325, 2600, -14950, 65780, -230230, 657800, -1562275, 3124550, -5311735, 7726160, -9657700, 10400600, -9657700, 7726160, -5311735, 3124550, -1562275, 657800, -230230, 65780, -14950, 2600, -325, 26, -1).
%F Sum_{d=1..26} C(27, d)*C(m/2-1, d-1)*C(26-d+m/2, m/2), where norm m is always even.
%K nonn,easy
%O 0,2
%A Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
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