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A005037
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Number of nonequivalent dissections of a polygon into n pentagons by nonintersecting diagonals rooted at a cell up to rotation.
(Formerly M4236)
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3
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1, 1, 6, 40, 285, 2126, 16380, 129456, 1043460, 8544965, 70893054, 594610536, 5033644070, 42952562100, 369061673400, 3190379997272, 27727712947836, 242135589539124, 2123541227823800, 18695484623015200, 165169213716082765
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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MATHEMATICA
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u[n_, k_, r_] := r*Binomial[(k-1)*n + r, n]/((k-1)*n + r);
T[n_, k_] := DivisorSum[GCD[n-1, k], EulerPhi[#]*u[(n-1)/#, k, k/#]&]/k;
a[n_] := T[n, 5];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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