%I M3283 #13 Mar 30 2012 16:45:08
%S 0,1,1,4,6,15,30,74,160,379,867,2057,4817,11465,27214,65102,155753,
%T 374208,900073,2170500,5240723,12676162,30697119,74435204,180679171
%N Number of symmetry sites in all planted 1,3-trees with 2n nodes.
%D Bailey, C. K.; Palmer, E. M.; Kennedy, J. W.; Points by degree and orbit size in chemical trees. II. Discrete Appl. Math. 5 (1983), no. 2, 157-164.
%D Bailey, C. K.; Fundamental orbits. Proceedings of the second West Coast conference on combinatorics, graph theory and computing (Eugene, Ore., 1983). Congr. Numer. 41 (1984), 149-152.
%D R. W. Robinson, personal communication.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%K nonn
%O 1,4
%A _N. J. A. Sloane_.