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A003741
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Number of perfect matchings (or domino tilings) in O_5 X P_2n.
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1
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40, 2197, 121735, 6748096, 374079619, 20737143595, 1149566489968, 63726386332735, 3532681575875629, 195834721732832344, 10856126548559080585, 601810968956118729913, 33361479413223474759160, 1849398508920455533993789, 102521677843870104359906191, 5683304262020707489694083600
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OFFSET
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1,1
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REFERENCES
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F. Faase, On the number of specific spanning subgraphs of the graphs G X P_n, Ars Combin. 49 (1998), 129-154.
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LINKS
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FORMULA
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If b(n) denotes the number of perfect matchings (or domino tilings) in O_5 X P_n we have:
b(1) = 0,
b(2) = 40,
b(3) = 0,
b(4) = 2197,
b(5) = 0,
b(6) = 121735,
b(7) = 0,
b(8) = 6748096,
b(9) = 0,
b(10) = 374079619,
b(11) = 0,
b(12) = 20737143595, and
b(n) = 65b(n-2) - 548b(n-4) + 995b(n-6) - 548b(n-8) + 65b(n-10) - b(n-12).
G.f.: -x*(x^5 -64*x^4 +523*x^3 -850*x^2 +403*x -40)/(x^6 -65*x^5 +548*x^4 -995*x^3 +548*x^2 -65*x +1). - Colin Barker, Aug 31 2012
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MATHEMATICA
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CoefficientList[Series[-(x^5 - 64 x^4 + 523 x^3 - 850 x^2 + 403 x - 40)/(x^6 - 65 x^5 + 548 x^4 - 995 x^3 + 548 x^2 - 65 x + 1), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 14 2013 *)
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PROG
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(Magma) I:=[40, 2197, 121735, 6748096, 374079619, 20737143595]; [n le 6 select I[n] else 65*Self(n-1)-548*Self(n-2)+995*Self(n-3)-548*Self(n-4)+65*Self(n-5)-Self(n-6): n in [1..20]]; // Vincenzo Librandi, Oct 14 2013
(PARI) Vec(-x*(x^5-64*x^4+523*x^3-850*x^2+403*x-40)/(x^6-65*x^5+548*x^4-995*x^3+548*x^2-65*x+1)+O(x^99)) \\ Charles R Greathouse IV, Jun 23 2020
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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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EXTENSIONS
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STATUS
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approved
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