A161127 - cp's OEIS frontend

A161127 Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k descents (n>=1; 1<=k<2n-1).

n	a(n)
1	1
2	1
3	1
4	1
5	1
6	3
7	7
8	3
9	1
10	1
11	6
12	27
13	37
14	27
15	6
16	1
17	1
18	10
19	76
20	220
21	331
22	220
23	76
24	10
25	1
26	1
27	15
28	176
29	897
30	2438
31	3341
32	2438
33	897
34	176
35	15
36	1
37	1
38	21
39	357
40	2885
41	12825
42	30807
43	41343
44	30807
45	12825
46	2885
47	357
48	21
49	1
50	1
51	28
52	658
53	7871
54	53312
55	203927
56	452931
57	589569

[1, 1, 1, 1, 1, 3, 7, 3, 1, 1, 6, 27, 37, 27, 6, 1, 1, 10, 76, 220, 331, 220, 76, 10, 1, 1, 15, 176, 897, 2438, 3341, 2438, 897, 176, 15, 1, 1, 21, 357, 2885, 12825, 30807, 41343, 30807, 12825, 2885, 357, 21, 1, 1, 28, 658, 7871, 53312, 203927, 452931, 589569]

cp's OEIS Frontend

A161127 Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k descents (n>=1; 1<=k<2n-1).

Table of values

List of values