A035866 Coordination sequence for A_40 lattice.

1, 1640, 673220, 123273880, 12774087510, 854286594072, 40098332182820, 1400550765961960, 38011151426301640, 828828255977397080, 14911158035799862332, 226193352868905599400, 2945866488164585776650

Offset

0,2

Links

Table of n, a(n) for n=0..12.

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 (40, -780, 9880, -91390, 658008, -3838380, 18643560, -76904685, 273438880, -847660528, 2311801440, -5586853480, 12033222880, -23206929840, 40225345056, -62852101650, 88732378800, -113380261800, 131282408400, -137846528820, 131282408400, -113380261800, 88732378800, -62852101650, 40225345056, -23206929840, 12033222880, -5586853480, 2311801440, -847660528, 273438880, -76904685, 18643560, -3838380, 658008, -91390, 9880, -780, 40, -1).

Formula

Sum_{d=1..40} C(41, d)*C(m/2-1, d-1)*C(40-d+m/2, m/2), where norm m is always even.

Crossrefs

Sequence in context: A043464 A002434 A146300 * A015340 A272127 A252197

Adjacent sequences: A035863 A035864 A035865 * A035867 A035868 A035869

Keyword

nonn,easy

Author

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

Status

approved