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A035847
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Coordination sequence for A_21 lattice.
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0
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1, 462, 53592, 2798642, 83945862, 1657762722, 23539760552, 255689552382, 2224042468032, 16045139112002, 98698280879352, 529244674992222, 2518877938240202, 10799525727846702, 42229092648830472
(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}^21 C(22, d) C(m/2-1, d-1) C(21-d+m/2, m/2), where norm m is always even
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CROSSREFS
| Sequence in context: A194718 A023912 A027565 * A140905 A025038 A028684
Adjacent sequences: A035844 A035845 A035846 * A035848 A035849 A035850
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KEYWORD
| nonn,easy
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AUTHOR
| Serra-Sagrista, Joan; jserra(AT)ccd.uab.es
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