A120984 - cp's OEIS frontend

A120984 Number of ternary trees with n edges and having no vertices of degree 1. A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.

n	a(n)
0	1
1	0
2	3
3	1
4	18
5	15
6	138
7	189
8	1218
9	2280
10	11826
11	27225
12	123013
13	325611
14	1346631
15	3919188
16	15318342
17	47563620
18	179405250
19	582336054
20	2148831144
21	7191954822
22	26193070008
23	89559039141
24	323765075223
25	1123859351610
26	4047466156545

[1, 0, 3, 1, 18, 15, 138, 189, 1218, 2280, 11826, 27225, 123013, 325611, 1346631, 3919188, 15318342, 47563620, 179405250, 582336054, 2148831144, 7191954822, 26193070008, 89559039141, 323765075223, 1123859351610, 4047466156545]

cp's OEIS Frontend

A120984 Number of ternary trees with n edges and having no vertices of degree 1. A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.

Table of values

List of values