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A035844
Coordination sequence for A_18 lattice.
0
1, 342, 29412, 1143762, 25727292, 384468534, 4175000796, 35078339106, 238815143406, 1364497268946, 6724224543708, 29206656395910, 113779617228060, 403237594259010, 1315394383751460, 3988232552194662
OFFSET
0,2
LINKS
R. Bacher, P. de la Harpe and B. Venkov, Séries de croissance et séries d'Ehrhart associées aux réseaux de racines, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.
J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
Joan Serra-Sagrista, Enumeration of lattice points in l_1 norm, Inf. Proc. Lett. 76 (1-2) (2000) 39-44.
Index entries for linear recurrences with constant coefficients, signature (18, -153, 816, -3060, 8568, -18564, 31824, -43758, 48620, -43758, 31824, -18564, 8568, -3060, 816, -153, 18, -1).
FORMULA
Sum_{d=1..18} C(19, d)*C(m/2-1, d-1)*C(18-d+m/2, m/2), where norm m is always even.
CROSSREFS
Sequence in context: A252235 A272380 A023909 * A028681 A005072 A112821
KEYWORD
nonn,easy
AUTHOR
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
STATUS
approved