%I A000677 M2366 N0936
%S A000677 0,0,1,0,1,1,3,4,11,20,51,108,267,619,1541,3762,9497,23907,61216,
%T A000677 157211,407919,1063398,2792026,7365532,19535887,52037837,139213244,
%U A000677 373820978,1007420841,2723783122,7387129661,20091790330,54793762295
%N A000677 Number of bicentered trees with n nodes.
%C A000677 See A000676 for more information.
%D A000677 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A000677 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000677 N. L. Biggs et al., Graph Theory 1736-1936, Oxford, 1976, p. 49.
%D A000677 A. Cayley, On the analytical forms called trees, with application to 
               the theory of chemical combinations, Reports British Assoc. Advance. 
               Sci. 45 (1875), 257-305 = Math. Papers, Vol. 9, 427-460 (see p. 438).
%H A000677 N. J. A. Sloane, <a href="b000677.txt">Table of n, a(n) for n = 0..200</
               a>
%H A000677 E. M. Rains and N. J. A. Sloane, <a href="http://www.cs.uwaterloo.ca/
               journals/JIS/index.html">On Cayley's Enumeration of Alkanes (or 4-Valent 
               Trees).</a>, J. Integer Sequences, Vol. 2 (1999), Article 99.1.1.
%H A000677 N. J. A. Sloane, <a href="a000677.txt">Maple program</a>
%H A000677 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               BicenteredTree.html">Link to a section of The World of Mathematics.</
               a>
%H A000677 <a href="Sindx_Tra.html#trees">Index entries for sequences related to 
               trees</a>
%p A000677 See link for Maple program.
%Y A000677 A000676+A000677 = A000055.
%Y A000677 Sequence in context: A036652 A097072 A049977 this_sequence A110865 A152982 
               A001642
%Y A000677 Adjacent sequences: A000674 A000675 A000676 this_sequence A000678 A000679 
               A000680
%K A000677 nonn,easy,nice
%O A000677 0,7
%A A000677 N. J. A. Sloane (njas(AT)research.att.com).