A035851 Coordination sequence for A_25 lattice.

1, 650, 105950, 7746050, 323371100, 8818775030, 171332460650, 2520031983950, 29356499303300, 280442899885850, 2258408187518990, 15677116400829650, 95542687574917700, 519065738821138550, 2546320423186207850

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 (25, -300, 2300, -12650, 53130, -177100, 480700, -1081575, 2042975, -3268760, 4457400, -5200300, 5200300, -4457400, 3268760, -2042975, 1081575, -480700, 177100, -53130, 12650, -2300, 300, -25, 1).

Formula

Sum_{d=1..25} C(26, d)*C(m/2-1, d-1)*C(25-d+m/2, m/2), where norm m is always even.

Crossrefs

Sequence in context: A158639 A162025 A251861 * A229797 A110836 A252388

Adjacent sequences: A035848 A035849 A035850 * A035852 A035853 A035854

Keyword

nonn,easy

Author

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

Status

approved