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A006681
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Number of binary phylogenetic trees with n labels.
(Formerly M3527)
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0
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1, 4, 16, 85, 646, 6664, 86731, 1354630, 24607816, 509000899, 11802833296, 303129872500, 8539567141561, 261785254856584, 8674697402099836, 308953306192527445, 11768768651529113506, 477433786852228938844
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,2
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REFERENCES
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Foulds, L. R.; Robinson, R. W. Enumeration of binary phylogenetic trees. Combinatorial mathematics, VIII (Geelong, 1980), pp. 187-202, Lecture Notes in Math., 884, Springer, Berlin-New York, 1981. Math. Rev. 83a:05071.
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) = Sum_{k=2..n} S(n, k) * A001147(k - 2) where S(n, m) are the Stirling numbers of the second kind. - Sean A. Irvine, Jun 16 2017
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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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