A055140 - cp's OEIS frontend

A055140 Triangle read by rows: T(n, k) = number of matchings of 2n people with partners (of either sex) such that exactly k couples are left together.

n	a(n)
0	1
1	0
2	1
3	2
4	0
5	1
6	8
7	6
8	0
9	1
10	60
11	32
12	12
13	0
14	1
15	544
16	300
17	80
18	20
19	0
20	1
21	6040
22	3264
23	900
24	160
25	30
26	0
27	1
28	79008
29	42280
30	11424
31	2100
32	280
33	42
34	0
35	1
36	1190672
37	632064
38	169120
39	30464
40	4200
41	448
42	56
43	0
44	1
45	20314880
46	10716048
47	2844288
48	507360
49	68544
50	7560
51	672
52	72
53	0
54	1

[1, 0, 1, 2, 0, 1, 8, 6, 0, 1, 60, 32, 12, 0, 1, 544, 300, 80, 20, 0, 1, 6040, 3264, 900, 160, 30, 0, 1, 79008, 42280, 11424, 2100, 280, 42, 0, 1, 1190672, 632064, 169120, 30464, 4200, 448, 56, 0, 1, 20314880, 10716048, 2844288, 507360, 68544, 7560, 672, 72, 0, 1]

cp's OEIS Frontend

A055140 Triangle read by rows: T(n, k) = number of matchings of 2n people with partners (of either sex) such that exactly k couples are left together.

Table of values

List of values