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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

R. Bacher, P. de la Harpe and B. Venkov, Series de croissance et series d'Ehrhart associees aux reseaux de racines, C. R. Acad. Sci. Paris, 325 (Series 1) (1997), 1137-1142.

J. Serra-Sagrista, Enumeration of lattice points in l_1 norm, Information Processing Letters, 76, no. 1-2 (2000), 39-44.

LINKS

Table of n, a(n) for n=0..15.

J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).

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

Adjacent sequences:  A035842 A035843 A035844 * A035846 A035847 A035848

KEYWORD

nonn,easy

AUTHOR

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

STATUS

approved

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Last modified September 26 13:34 EDT 2021. Contains 347668 sequences. (Running on oeis4.)