A120989 - cp's OEIS frontend

A120989 Level of the first leaf (in preorder traversal) of a binary tree, summed over all binary trees with n edges. A binary tree is a rooted tree in which each vertex has at most two children and each child of a vertex is designated as its left or right child.

n	a(n)
1	2
2	9
3	34
4	123
5	440
6	1573
7	5642
8	20332
9	73644
10	268090
11	980628
12	3603065
13	13293540
14	49234605
15	182991450
16	682341000
17	2551955340
18	9570762990
19	35985909180
20	135628219350
21	512302356384
22	1939078493154
23	7353556121924
24	27936898370248
25	106313496846200

[2, 9, 34, 123, 440, 1573, 5642, 20332, 73644, 268090, 980628, 3603065, 13293540, 49234605, 182991450, 682341000, 2551955340, 9570762990, 35985909180, 135628219350, 512302356384, 1939078493154, 7353556121924, 27936898370248, 106313496846200]

cp's OEIS Frontend

A120989 Level of the first leaf (in preorder traversal) of a binary tree, summed over all binary trees with n edges. A binary tree is a rooted tree in which each vertex has at most two children and each child of a vertex is designated as its left or right child.

Table of values

List of values