A336524 - cp's OEIS frontend

A336524 Triangular array read by rows. T(n,k) is the number of unlabeled binary trees with n internal nodes and exactly k distinguished external nodes (leaves) for 0 <= k <= n+1 and n >= 0.

n	a(n)
0	1
1	1
2	1
3	2
4	1
5	2
6	6
7	6
8	2
9	5
10	20
11	30
12	20
13	5
14	14
15	70
16	140
17	140
18	70
19	14
20	42
21	252
22	630
23	840
24	630
25	252
26	42
27	132
28	924
29	2772
30	4620
31	4620
32	2772
33	924
34	132
35	429
36	3432
37	12012
38	24024
39	30030
40	24024
41	12012
42	3432
43	429

[1, 1, 1, 2, 1, 2, 6, 6, 2, 5, 20, 30, 20, 5, 14, 70, 140, 140, 70, 14, 42, 252, 630, 840, 630, 252, 42, 132, 924, 2772, 4620, 4620, 2772, 924, 132, 429, 3432, 12012, 24024, 30030, 24024, 12012, 3432, 429]

cp's OEIS Frontend

A336524 Triangular array read by rows. T(n,k) is the number of unlabeled binary trees with n internal nodes and exactly k distinguished external nodes (leaves) for 0 <= k <= n+1 and n >= 0.

Table of values

List of values