A162974 - cp's OEIS frontend

A162974 Triangle read by rows: T(n,k) is the number of derangements of {1,2,...,n} having k cycles of length 2 (0 <= k <= floor(n/2)).

n	a(n)
0	1
1	0
2	0
3	1
4	2
5	0
6	6
7	0
8	3
9	24
10	20
11	0
12	160
13	90
14	0
15	15
16	1140
17	504
18	210
19	0
20	8988
21	4480
22	1260
23	0
24	105
25	80864
26	41040
27	9072
28	2520
29	0
30	809856
31	404460
32	100800
33	18900
34	0
35	945
36	8907480
37	4447520
38	1128600
39	166320
40	34650
41	0
42	106877320
43	53450496
44	13347180
45	2217600

[1, 0, 0, 1, 2, 0, 6, 0, 3, 24, 20, 0, 160, 90, 0, 15, 1140, 504, 210, 0, 8988, 4480, 1260, 0, 105, 80864, 41040, 9072, 2520, 0, 809856, 404460, 100800, 18900, 0, 945, 8907480, 4447520, 1128600, 166320, 34650, 0, 106877320, 53450496, 13347180, 2217600]

cp's OEIS Frontend

A162974 Triangle read by rows: T(n,k) is the number of derangements of {1,2,...,n} having k cycles of length 2 (0 <= k <= floor(n/2)).

Table of values

List of values