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%I #16 Sep 06 2023 01:56:35
%S 1,380,36290,1564460,38906870,640622012,7634582090,70098276620,
%T 519252051080,3214138597460,17088309885542,79759293448100,
%U 332648955112250,1257743358034100,4363052456797550,14025412751733092
%N Coordination sequence for A_19 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_19">Index entries for linear recurrences with constant coefficients</a>, signature (19, -171, 969, -3876, 11628, -27132, 50388, -75582, 92378, -92378, 75582, -50388, 27132, -11628, 3876, -969, 171, -19, 1).
%F Sum_{d=1..19} C(20, d)*C(m/2-1, d-1)*C(19-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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