%I A006570 M1475
%S A006570 1,2,5,15,48,166,596,2221,8472
%N A006570 From trees with valency <= 3.
%D A006570 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006570 P. J. Cameron, Some treelike objects, Quart. J. Math. Oxford, 38 (1987), 
               155-183.
%H A006570 <a href="Sindx_Tra.html#trees">Index entries for sequences related to 
               trees</a>
%Y A006570 Sequence in context: A145072 A149927 A035350 this_sequence A149928 A003430 
               A149929
%Y A006570 Adjacent sequences: A006567 A006568 A006569 this_sequence A006571 A006572 
               A006573
%K A006570 nonn
%O A006570 1,2
%A A006570 N. J. A. Sloane (njas(AT)research.att.com).