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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A303271 Number of ordered rooted trees with n non-root nodes such that the maximal outdegree equals three. 2
1, 4, 15, 53, 182, 616, 2070, 6930, 23166, 77429, 258973, 867230, 2908633, 9772556, 32896088, 110949072, 374934201, 1269505482, 4306750577, 14638006449, 49843505965, 170021694271, 580954640775, 1988357053020, 6816047416230, 23400699072231, 80455436055699 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 3..1802

FORMULA

a(n) = A036765(n) - A001006(n).

MAPLE

b:= proc(u, o, k) option remember; `if`(u+o=0, 1,

      add(b(u-j, o+j-1, k), j=1..min(1, u))+

      add(b(u+j-1, o-j, k), j=1..min(k, o)))

    end:

a:= n-> b(0, n, 3)-b(0, n, 2):

seq(a(n), n=3..35);

CROSSREFS

Column k=3 of A203717.

Cf. A001006, A036765.

Sequence in context: A162978 A171309 A210781 * A289802 A071719 A289927

Adjacent sequences:  A303268 A303269 A303270 * A303272 A303273 A303274

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Apr 20 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 16 22:05 EST 2019. Contains 329208 sequences. (Running on oeis4.)