A035848 Coordination sequence for A_22 lattice.

1, 506, 64262, 3670018, 120177024, 2584888350, 39868752506, 468969729382, 4403475647758, 34183012888134, 225524301678170, 1292986222651646, 6559731002608432, 29893343687161218, 123905004120349254

Offset

0,2

Links

Table of n, a(n) for n=0..14.

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 (22, -231, 1540, -7315, 26334, -74613, 170544, -319770, 497420, -646646, 705432, -646646, 497420, -319770, 170544, -74613, 26334, -7315, 1540, -231, 22, -1).

Formula

Sum_{d=1..22} C(23, d)*C(m/2-1, d-1)*C(22-d+m/2, m/2), where norm m is always even.

Crossrefs

Sequence in context: A122267 A204946 A023913 * A028685 A152524 A236004

Adjacent sequences: A035845 A035846 A035847 * A035849 A035850 A035851

Keyword

nonn,easy

Author

Joan Serra-Sagrista (jserra(AT)ccd.uab.es)

Status

approved