A082680 - cp's OEIS frontend

A082680 Triangle read by rows: T(n,k) is the number of 2-stack sortable n-permutations with k runs.

n	a(n)
1	1
2	1
3	1
4	1
5	4
6	1
7	1
8	10
9	10
10	1
11	1
12	20
13	49
14	20
15	1
16	1
17	35
18	168
19	168
20	35
21	1
22	1
23	56
24	462
25	900
26	462
27	56
28	1
29	1
30	84
31	1092
32	3630
33	3630
34	1092
35	84
36	1
37	1
38	120
39	2310
40	12012
41	20449
42	12012
43	2310
44	120
45	1
46	1
47	165
48	4488
49	34320
50	91091
51	91091
52	34320
53	4488
54	165
55	1
56	1
57	220
58	8151
59	87516
60	340340
61	529984
62	340340
63	87516
64	8151
65	220
66	1

[1, 1, 1, 1, 4, 1, 1, 10, 10, 1, 1, 20, 49, 20, 1, 1, 35, 168, 168, 35, 1, 1, 56, 462, 900, 462, 56, 1, 1, 84, 1092, 3630, 3630, 1092, 84, 1, 1, 120, 2310, 12012, 20449, 12012, 2310, 120, 1, 1, 165, 4488, 34320, 91091, 91091, 34320, 4488, 165, 1, 1, 220, 8151, 87516, 340340, 529984, 340340, 87516, 8151, 220, 1]

cp's OEIS Frontend

A082680 Triangle read by rows: T(n,k) is the number of 2-stack sortable n-permutations with k runs.

Table of values

List of values