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A035846
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Coordination sequence for A_20 lattice.
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0
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1, 420, 44310, 2107140, 57671880, 1041949020, 13577591370, 135798494460, 1091481669390, 7302195414780, 41800229045610, 209294745286620, 933146517188760, 3759426449644740, 13853429338548630, 47171740235162340
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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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.
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LINKS
| J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (Abstract, pdf, ps).
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FORMULA
| sum_{d=1}^20 C(21, d) C(m/2-1, d-1) C(20-d+m/2, m/2), where norm m is always even
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CROSSREFS
| Sequence in context: A023911 A135340 A135380 * A046167 A059951 A028683
Adjacent sequences: A035843 A035844 A035845 * A035847 A035848 A035849
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KEYWORD
| nonn,easy
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AUTHOR
| Serra-Sagrista, Joan; jserra(AT)ccd.uab.es
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