A035853 Coordination sequence for A_27 lattice.

1, 756, 143262, 12161268, 588265524, 18537751260, 414778201866, 6999447089052, 93165559355988, 1012535574855924, 9235450619189550, 72289879424643636, 494595518082468012, 3003613286791211388

Offset

0,2

Links

Table of n, a(n) for n=0..13.

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 (27, -351, 2925, -17550, 80730, -296010, 888030, -2220075, 4686825, -8436285, 13037895, -17383860, 20058300, -20058300, 17383860, -13037895, 8436285, -4686825, 2220075, -888030, 296010, -80730, 17550, -2925, 351, -27, 1).

Formula

Sum_{d=1..27} C(28, d)*C(m/2-1, d-1)*C(27-d+m/2, m/2), where norm m is always even.

Crossrefs

Sequence in context: A269140 A269198 A269106 * A269286 A289570 A269934

Adjacent sequences: A035850 A035851 A035852 * A035854 A035855 A035856

Keyword

nonn,easy

Author

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

Status

approved