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A006430
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Number of loopless tree-rooted planar maps with 5 vertices and n faces and no isthmuses.
(Formerly M4036)
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2
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0, 5, 360, 7350, 73700, 474588, 2292790, 9046807, 30676440, 92393015, 252872984, 639382605, 1512137536, 3377126024, 7176513960, 14599539314, 28575632350, 54036739617, 99069119952, 176618150000, 306965183268, 521265871700, 866527603370, 1412513294049
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OFFSET
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1,2
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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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a(n) = n*(n + 2)*(n + 3)*(23*n^10 + 963*n^9 + 17544*n^8 + 147952*n^7 + 481675*n^6 - 1052153*n^5 - 7850914*n^4 - 2900162*n^3 + 60869272*n^2 + 37067400*n - 179920800)/(2*11!) for n > 1.
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PROG
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(PARI) a(n)={if(n<2, 0, n*(n + 2)*(n + 3)*(23*n^10 + 963*n^9 + 17544*n^8 + 147952*n^7 + 481675*n^6 - 1052153*n^5 - 7850914*n^4 - 2900162*n^3 + 60869272*n^2 + 37067400*n - 179920800)/(2*11!))} \\ Andrew Howroyd, Apr 03 2021
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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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