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A010024
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Coordination sequence for squashed {D_5}* lattice, perhaps the smallest example of a "non-superficial" lattice.
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1
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1, 12, 72, 292, 862, 2052, 4212, 7772, 13242, 21212, 32352, 47412, 67222, 92692, 124812, 164652, 213362, 272172, 342392, 425412, 522702, 635812, 766372, 916092, 1086762, 1280252, 1498512, 1743572, 2017542, 2322612, 2661052, 3035212, 3447522, 3900492, 4396712
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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).
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FORMULA
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a(n) = 10/3*n^4-5/3*n^3+20/3*n^2+5/3*n+2 for n>0 (from Maple section).
G.f.: -(x^5+7*x^4+42*x^3+22*x^2+7*x+1)/(x^5-5*x^4+10*x^3-10*x^2+5*x-1).
E.g.f.: 1/3*(10*x^4+55*x^3+75*x^2+30*x+6)*e^x-1. (End)
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MAPLE
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10/3*n^4-5/3*n^3+20/3*n^2+5/3*n+2;
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PROG
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(Magma) [1] cat [10/3*n^4-5/3*n^3+20/3*n^2+5/3*n+2: n in [1..40]]; // Vincenzo Librandi, Aug 03 2015
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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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