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A035876
Coordination sequence for A_50 lattice.
1
1, 2550, 1626900, 462400850, 74214929700, 7664751475110, 553532399900300, 29615721096973650, 1225039098412340850, 40483994261907371450, 1097141899359944015580, 24907942311608525171550, 482175421833854221370900
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.
Index entries for linear recurrences with constant coefficients, signature (50, -1225, 19600, -230300, 2118760, -15890700, 99884400, -536878650, 2505433700, -10272278170, 37353738800, -121399651100, 354860518600, -937845656300, 2250829575120, -4923689695575, 9847379391150, -18053528883775, 30405943383200, -47129212243960, 67327446062800, -88749815264600, 108043253365600, -121548660036300, 126410606437752, -121548660036300, 108043253365600, -88749815264600, 67327446062800, -47129212243960, 30405943383200, -18053528883775, 9847379391150, -4923689695575, 2250829575120, -937845656300, 354860518600, -121399651100, 37353738800, -10272278170, 2505433700, -536878650, 99884400, -15890700, 2118760, -230300, 19600, -1225, 50, -1).
FORMULA
Sum_{d=1..50} C(51, d)*C(m/2-1, d-1)*C(50-d+m/2, m/2), where norm m is always even.
CROSSREFS
Sequence in context: A250686 A307473 A327771 * A072435 A050413 A050544
KEYWORD
nonn,easy
AUTHOR
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
EXTENSIONS
a(9)-a(10) corrected, a(11)-a(12) added by Ray Chandler, Jan 19 2016
STATUS
approved