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A035845
Coordination sequence for A_19 lattice.
0
1, 380, 36290, 1564460, 38906870, 640622012, 7634582090, 70098276620, 519252051080, 3214138597460, 17088309885542, 79759293448100, 332648955112250, 1257743358034100, 4363052456797550, 14025412751733092
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 (19, -171, 969, -3876, 11628, -27132, 50388, -75582, 92378, -92378, 75582, -50388, 27132, -11628, 3876, -969, 171, -19, 1).
FORMULA
Sum_{d=1..19} C(20, d)*C(m/2-1, d-1)*C(19-d+m/2, m/2), where norm m is always even.
CROSSREFS
Sequence in context: A214145 A185493 A023910 * A028682 A222163 A297543
KEYWORD
nonn,easy
AUTHOR
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
STATUS
approved