A216255 - cp's OEIS frontend

A216255 Triangle read by rows: T(n,k) is the number of labeled rooted trees of height at most 2 that have exactly k nodes at a distance 2 from the root; n>=1, 0<=k<=n-1.

n	a(n)
1	1
2	2
3	0
4	3
5	6
6	0
7	4
8	24
9	12
10	0
11	5
12	60
13	120
14	20
15	0
16	6
17	120
18	540
19	480
20	30
21	0
22	7
23	210
24	1680
25	3780
26	1680
27	42
28	0
29	8
30	336
31	4200
32	17920
33	22680
34	5376
35	56
36	0
37	9
38	504
39	9072
40	63000
41	161280
42	122472
43	16128
44	72
45	0
46	10
47	720
48	17640
49	181440
50	787500
51	1290240
52	612360
53	46080
54	90
55	0

[1, 2, 0, 3, 6, 0, 4, 24, 12, 0, 5, 60, 120, 20, 0, 6, 120, 540, 480, 30, 0, 7, 210, 1680, 3780, 1680, 42, 0, 8, 336, 4200, 17920, 22680, 5376, 56, 0, 9, 504, 9072, 63000, 161280, 122472, 16128, 72, 0, 10, 720, 17640, 181440, 787500, 1290240, 612360, 46080, 90, 0]

cp's OEIS Frontend

A216255 Triangle read by rows: T(n,k) is the number of labeled rooted trees of height at most 2 that have exactly k nodes at a distance 2 from the root; n>=1, 0<=k<=n-1.

Table of values

List of values