A037224 - cp's OEIS frontend

A037224 Number of permutations p of {1,2,3...,n} that are fixed points under the operation of first reversing p, then taking the inverse.

n	a(n)
1	1
2	0
3	0
4	2
5	2
6	0
7	0
8	12
9	12
10	0
11	0
12	120
13	120
14	0
15	0
16	1680
17	1680
18	0
19	0
20	30240
21	30240
22	0
23	0
24	665280
25	665280
26	0
27	0
28	17297280
29	17297280
30	0
31	0
32	518918400
33	518918400
34	0
35	0
36	17643225600
37	17643225600
38	0
39	0
40	670442572800
41	670442572800
42	0
43	0
44	28158588057600

[1, 0, 0, 2, 2, 0, 0, 12, 12, 0, 0, 120, 120, 0, 0, 1680, 1680, 0, 0, 30240, 30240, 0, 0, 665280, 665280, 0, 0, 17297280, 17297280, 0, 0, 518918400, 518918400, 0, 0, 17643225600, 17643225600, 0, 0, 670442572800, 670442572800, 0, 0, 28158588057600]

cp's OEIS Frontend

A037224 Number of permutations p of {1,2,3...,n} that are fixed points under the operation of first reversing p, then taking the inverse.

Table of values

List of values