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A003228 Endpoints in trees with n nodes.
(Formerly M0351)

%I M0351

%S 1,2,2,5,9,21,43,101,226,556,1333,3365,8500,22007,57258,151264,401761,

%T 1077063,2902599,7871250,21440642,58672589,161155637,444240627,

%U 1228400744,3406668865,9472308269,26402207803,73755064178

%N Endpoints in trees with n nodes.

%D R. W. Robinson and A. J. Schwenk, The distribution of trees in a large random tree, Discr. Math., 12 (1975), 359-.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TreeLeaf.html">Tree Leaf.</a>

%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>

%F 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.

%Y Cf. A000055, A003227, A055290.

%K nonn

%O 1,2

%A _N. J. A. Sloane_.

%E Corrected and extended with formula by _Christian G. Bower_, May 25 2000

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Last modified October 14 18:28 EDT 2019. Contains 328022 sequences. (Running on oeis4.)