A052120 - OEIS

A052120

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

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,10

COMMENTS

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

LINKS

Eric Weisstein's World of Mathematics, Cayley Tree.

Eric Weisstein's World of Mathematics, Trivalent Tree

CROSSREFS

See A000672, the subsequence of even-numbered terms, which is the main entry for this sequence, for more terms, references, etc.

KEYWORD

nonn,easy

AUTHOR

STATUS

approved