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Search: id:A007899
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| A007899 |
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Coordination sequence for hexagonal close-packing. |
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+0
1
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| 1, 12, 44, 96, 170, 264, 380, 516, 674, 852, 1052, 1272, 1514, 1776, 2060, 2364, 2690, 3036, 3404, 3792, 4202, 4632, 5084, 5556, 6050, 6564, 7100, 7656, 8234, 8832, 9452, 10092, 10754, 11436, 12140, 12864, 13610
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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M. O'Keeffe, Coordination sequences for lattices, Zeit. f. Krist., 210 (1995), 905-908.
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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 (Abstract, pdf, ps).
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MAPLE
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floor( 21*n^2 / 2 ) + 2;
G.f.: (x^4+10*x^3+20*x^2+10*x+1)/(1-x)^3/(x+1).
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CROSSREFS
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Sequence in context: A009790 A009519 A106808 this_sequence A100156 A009785 A135710
Adjacent sequences: A007896 A007897 A007898 this_sequence A007900 A007901 A007902
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com) and J. H. Conway (conway(AT)math.princeton.edu)
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