%I A003228 M0351
%S A003228 1,2,2,5,9,21,43,101,226,556,1333,3365,8500,22007,57258,151264,401761,
%T A003228 1077063,2902599,7871250,21440642,58672589,161155637,444240627,
%U A003228 1228400744,3406668865,9472308269,26402207803,73755064178
%N A003228 Endpoints in trees with n nodes.
%D A003228 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003228 R. W. Robinson and A. J. Schwenk, The distribution of trees in a large 
               random tree, Discr. Math., 12 (1975), 359-.
%H A003228 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               TreeLeaf.html">Link to a section of The World of Mathematics.</a>
%H A003228 <a href="Sindx_Tra.html#trees">Index entries for sequences related to 
               trees</a>
%F A003228 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 A003228 Cf. A000055, A003227, A055290.
%Y A003228 Sequence in context: A052969 A002990 A060405 this_sequence A110182 A075125 
               A081374
%Y A003228 Adjacent sequences: A003225 A003226 A003227 this_sequence A003229 A003230 
               A003231
%K A003228 nonn
%O A003228 1,2
%A A003228 N. J. A. Sloane (njas(AT)research.att.com).
%E A003228 Corrected and extended with formula by Christian G. Bower (bowerc(AT)usa.net), 
               May 25 2000