A277081 - cp's OEIS frontend

A277081 Irregular triangle read by rows: T(n,k) = number of size k subsets of S_n that remain unchanged under the operation of replacing a permutation with its inverse.

n	a(n)
0	1
1	1
2	1
3	1
4	1
5	2
6	1
7	1
8	4
9	7
10	8
11	7
12	4
13	1
14	1
15	10
16	52
17	190
18	546
19	1302
20	2660
21	4754
22	7535
23	10692
24	13672
25	15820
26	16604
27	15820
28	13672
29	10692
30	7535
31	4754
32	2660
33	1302
34	546
35	190
36	52
37	10
38	1
39	1
40	26
41	372
42	3822
43	31306
44	216086
45	1300420
46	6981650
47	33992275
48	151945820

[1, 1, 1, 1, 1, 2, 1, 1, 4, 7, 8, 7, 4, 1, 1, 10, 52, 190, 546, 1302, 2660, 4754, 7535, 10692, 13672, 15820, 16604, 15820, 13672, 10692, 7535, 4754, 2660, 1302, 546, 190, 52, 10, 1, 1, 26, 372, 3822, 31306, 216086, 1300420, 6981650, 33992275, 151945820]

cp's OEIS Frontend

A277081 Irregular triangle read by rows: T(n,k) = number of size k subsets of S_n that remain unchanged under the operation of replacing a permutation with its inverse.

Table of values

List of values