A161121 - cp's OEIS frontend

A161121 Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k cycles with entries of the same parity (0 <= k <= 2*floor(n/2)).

n	a(n)
0	1
1	1
2	2
3	0
4	1
5	6
6	0
7	9
8	24
9	0
10	72
11	0
12	9
13	120
14	0
15	600
16	0
17	225
18	720
19	0
20	5400
21	0
22	4050
23	0
24	225
25	5040
26	0
27	52920
28	0
29	66150
30	0
31	11025
32	40320
33	0
34	564480
35	0
36	1058400
37	0
38	352800
39	0
40	11025
41	362880
42	0
43	6531840
44	0
45	17146080
46	0
47	9525600
48	0
49	893025
50	3628800
51	0
52	81648000
53	0

[1, 1, 2, 0, 1, 6, 0, 9, 24, 0, 72, 0, 9, 120, 0, 600, 0, 225, 720, 0, 5400, 0, 4050, 0, 225, 5040, 0, 52920, 0, 66150, 0, 11025, 40320, 0, 564480, 0, 1058400, 0, 352800, 0, 11025, 362880, 0, 6531840, 0, 17146080, 0, 9525600, 0, 893025, 3628800, 0, 81648000, 0]

cp's OEIS Frontend

A161121 Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k cycles with entries of the same parity (0 <= k <= 2*floor(n/2)).

Table of values

List of values