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Search: id:A003228
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| A003228 |
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Endpoints in trees with n nodes.
(Formerly M0351)
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+0
5
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| 1, 2, 2, 5, 9, 21, 43, 101, 226, 556, 1333, 3365, 8500, 22007, 57258, 151264, 401761, 1077063, 2902599, 7871250, 21440642, 58672589, 161155637, 444240627, 1228400744, 3406668865, 9472308269, 26402207803, 73755064178
(list; graph; listen)
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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).
R. W. Robinson and A. J. Schwenk, The distribution of trees in a large random tree, Discr. Math., 12 (1975), 359-.
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LINKS
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Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Index entries for sequences related to trees
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FORMULA
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a(n)=sum{k=1 to n} k*c(n, k), where c(n, k) = A055290(n, k) has g.f. (1-x+x*y)*B(x, y)+(1/2)*(B(x^2, y^2)-B(x, y)^2) and B(x, y) is g.f. for A055372.
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CROSSREFS
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Cf. A000055, A003227, A055290.
Sequence in context: A052969 A002990 A060405 this_sequence A110182 A075125 A081374
Adjacent sequences: A003225 A003226 A003227 this_sequence A003229 A003230 A003231
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Corrected and extended with formula by Christian G. Bower (bowerc(AT)usa.net), May 25 2000
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