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A035755
Coordination sequence for C_18 lattice.
1
1, 648, 70416, 3116952, 76117536, 1202893992, 13591279920, 117561917880, 818017823808, 4752575891144, 23727649169232, 104129375982552, 409027707560544, 1459400559786216, 4787137642562928, 14581451741758968, 41589736720488576, 111867495074401032, 285475524009208720
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.
FORMULA
a(n) = [x^(2n)] ((1+x)/(1-x))^18.
CROSSREFS
Sequence in context: A034619 A185270 A250343 * A107551 A202056 A229155
KEYWORD
nonn,easy
AUTHOR
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
EXTENSIONS
Recomputed by N. J. A. Sloane, Nov 25 1998
STATUS
approved