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A006415
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Number of nonseparable toroidal tree-rooted maps with n + 3 edges and n + 1 vertices.
(Formerly M3705)
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2
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OFFSET
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0,1
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COMMENTS
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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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FORMULA
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Conjecture: a(n) = 4 * binomial(n + 4, n) + 84 * binomial(n + 4, n - 1) + 456 * binomial(n + 4, n - 2) + 996 * binomial(n + 4, n - 3) + 950 * binomial(n + 4, n - 4) + 330 * binomial(n + 5, n - 5). - Sean A. Irvine, Apr 03 2017
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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