A292230 Number of (unlabeled) rooted trees with n leaf nodes and without unary nodes such that the maximum of the node outdegrees equals four.

1, 2, 7, 22, 72, 230, 751, 2442, 8006, 26280, 86604, 285994, 946866, 3140812, 10438300, 34747649, 115849084, 386779317, 1292998720, 4327654320, 14500841169, 48639319376, 163308287353, 548820437392, 1845999502151, 6214297279692, 20935992503127, 70586182742450

Offset: 4

Author

Alois P. Heinz, Sep 12 2017

Keywords

• nonn

Examples

			: a(6) = 7:
:           o             o            o             o
:          / \          /   \        /( )\         / | \
:         o   N        o     N      o N N N       o  N  N
:        / \         /( )\         / \          /( )\
:       o   N       o N N N       o   N        N N N N
:     /( )\        ( )           ( )
:    N N N N       N N           N N
:
:          o            o              o
:        /   \        /( )\         / ( \ \
:       o     o      o N N N      o   o  N N
:     /( )\  ( )    /|\          ( ) ( )
:    N N N N N N   N N N         N N N N
:
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 4..1000
• Index entries for sequences related to rooted trees

Crossrefs

Column k=4 of A292086.

Programs

Maple

b:= proc(n, i, v, k) option remember; `if`(n=0,
      `if`(v=0, 1, 0), `if`(i<1 or v<1 or n A(n, 4)-A(n, 3):
seq(a(n), n=4..35);