

A052120


Number of 3valent trees (= boron trees or binary trees) with n nodes.


1



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, 552, 0, 1132, 0, 2410, 0, 5098, 0, 11020, 0, 23846, 0
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OFFSET

1,10


COMMENTS

Trees with n nodes each of valency either 1 or 3.


LINKS

Table of n, a(n) for n=1..41.
Eric Weisstein's World of Mathematics, Cayley Tree.
Eric Weisstein's World of Mathematics, Trivalent Tree
Index entries for sequences related to trees


CROSSREFS

See A000672, the subsequence of evennumbered terms, which is the main entry for this sequence, for more terms, references, etc.
Sequence in context: A201863 A035385 A051629 * A179461 A238763 A029186
Adjacent sequences: A052117 A052118 A052119 * A052121 A052122 A052123


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane.


STATUS

approved



