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A035853
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Coordination sequence for A_27 lattice.
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0
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1, 756, 143262, 12161268, 588265524, 18537751260, 414778201866, 6999447089052, 93165559355988, 1012535574855924, 9235450619189550, 72289879424643636, 494595518082468012, 3003613286791211388
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OFFSET
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0,2
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LINKS
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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 (27, -351, 2925, -17550, 80730, -296010, 888030, -2220075, 4686825, -8436285, 13037895, -17383860, 20058300, -20058300, 17383860, -13037895, 8436285, -4686825, 2220075, -888030, 296010, -80730, 17550, -2925, 351, -27, 1).
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FORMULA
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Sum_{d=1..27} C(28, d)*C(m/2-1, d-1)*C(27-d+m/2, m/2), where norm m is always even.
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
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STATUS
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approved
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