login
This site is supported by donations to The OEIS Foundation.
Logo

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A052120 Number of 3-valent 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 (list; graph; refs; listen; history; internal format)
OFFSET

1,10

COMMENTS

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

LINKS

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Index entries for sequences related to trees

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.

Sequence in context: A201863 A035385 A051629 * A179461 A029186 A072680

Adjacent sequences:  A052117 A052118 A052119 * A052121 A052122 A052123

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 17 02:48 EST 2012. Contains 205978 sequences.