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A008389
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Coordination sequence for A_7 lattice.
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2
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1, 56, 812, 5768, 26474, 91112, 256508, 623576, 1356194, 2703512, 5025692, 8823080, 14768810, 23744840, 36881420, 55599992, 81659522, 117206264, 164826956, 227605448, 309182762, 413820584, 546468188, 712832792, 919453346
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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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G.f.: (1+x)*(1+48*x+393*x^2+832*x^3+393*x^4+48*x^5+x^6)/(1-x)^7. - Colin Barker, Sep 26 2012
a(n) = 2 + n^2*(143*n^4 +770*n^2 +707)/30 with n>0, a(0)=1. - Bruno Berselli, Sep 26 2012
E.g.f.: -1 + (1/30)*(60 +1620*x +10530*x^2 +17490*x^3 +10065*x^4 +2145*x^5 +143*x^6)*exp(x). - G. C. Greubel, May 26 2023
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MAPLE
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1, seq(2 +n^2*(143*n^4 +770*n^2 +707)/30, n=1..50);
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MATHEMATICA
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Table[n^2*(143*n^4 +770*n^2 +707)/30 +2 -Boole[n==0], {n, 0, 40}] (* G. C. Greubel, May 26 2023 *)
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PROG
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(Magma) [1] cat [2 +n^2*(143*n^4 +770*n^2 +707)/30: n in [1..40]]; // G. C. Greubel, May 26 2023
(SageMath) [2 +n^2*(143*n^4 +770*n^2 +707)/30 -int(n==0) for n in range(41)] // G. C. Greubel, May 26 2023
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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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