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%I #12 Mar 06 2020 00:04:05
%S 1,1,0,1,0,1,0,1,0,2,0,2,0,4,0,6,0,11,0,18,0,37,0,66,0,135,0,265,0,
%T 552,0,1132,0,2410,0,5098,0,11020,0,23846,0
%N Number of 3-valent trees (= boron trees or binary trees) with n nodes.
%C Trees with n nodes each of valency either 1 or 3.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CayleyTree.html">Cayley Tree.</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TrivalentTree.html">Trivalent Tree</a>
%H <a href="/index/Tra#trees">Index entries for sequences related to trees</a>
%Y See A000672, the subsequence of even-numbered terms, which is the main entry for this sequence, for more terms, references, etc.
%K nonn,easy
%O 1,10
%A _N. J. A. Sloane_
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