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A008386
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Crystal ball sequence for A_5 lattice.
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4
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1, 31, 271, 1281, 4251, 11253, 25493, 51563, 95693, 166003, 272755, 428605, 648855, 951705, 1358505, 1894007, 2586617, 3468647, 4576567, 5951257, 7638259, 9688029, 12156189, 15103779, 18597509
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OFFSET
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0,2
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COMMENTS
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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).
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FORMULA
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a(n) = (2*n+1)*(63*n^4+126*n^3+217*n^2+154*n+60)/60. - T. D. Noe, Apr 29 2007
G.f.: (1+x)*(1+24*x+76*x^2+24*x^3+x^4)/(1-x)^6. - Colin Barker, Mar 16 2012
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MATHEMATICA
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LinearRecurrence[{6, -15, 20, -15, 6, -1}, {1, 31, 271, 1281, 4251, 11253}, 30] (* Harvey P. Dale, Apr 08 2018 *)
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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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STATUS
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approved
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