A221877 - cp's OEIS frontend

A221877 Triangle read by rows: T(n,k) = number of order-preserving or order-reversing full contraction mappings (of an n-chain) with height exactly k.

n	a(n)
1	1
2	2
3	2
4	3
5	8
6	2
7	4
8	18
9	12
10	2
11	5
12	32
13	36
14	16
15	2
16	6
17	50
18	80
19	60
20	20
21	2
22	7
23	72
24	150
25	160
26	90
27	24
28	2
29	8
30	98
31	252
32	350
33	280
34	126
35	28
36	2
37	9
38	128
39	392
40	672
41	700
42	448
43	168
44	32
45	2
46	10
47	162
48	576
49	1176
50	1512
51	1260
52	672
53	216
54	36
55	2

[1, 2, 2, 3, 8, 2, 4, 18, 12, 2, 5, 32, 36, 16, 2, 6, 50, 80, 60, 20, 2, 7, 72, 150, 160, 90, 24, 2, 8, 98, 252, 350, 280, 126, 28, 2, 9, 128, 392, 672, 700, 448, 168, 32, 2, 10, 162, 576, 1176, 1512, 1260, 672, 216, 36, 2]

cp's OEIS Frontend

A221877 Triangle read by rows: T(n,k) = number of order-preserving or order-reversing full contraction mappings (of an n-chain) with height exactly k.

Table of values

List of values