A176127 - cp's OEIS frontend

A176127 The number of permutations of {1,2,...,n,1,2,...,n} with the property that there are k numbers between the two k's in the set for k=1,...,n.

n	a(n)
1	0
2	0
3	2
4	2
5	0
6	0
7	52
8	300
9	0
10	0
11	35584
12	216288
13	0
14	0
15	79619280
16	653443600
17	0
18	0
19	513629782560
20	5272675722400
21	0
22	0
23	7598911885030976
24	93690316113031872
25	0
26	0
27	223367222197529806464
28	3214766521218764786304
29	0
30	0

[0, 0, 2, 2, 0, 0, 52, 300, 0, 0, 35584, 216288, 0, 0, 79619280, 653443600, 0, 0, 513629782560, 5272675722400, 0, 0, 7598911885030976, 93690316113031872, 0, 0, 223367222197529806464, 3214766521218764786304, 0, 0]

cp's OEIS Frontend

A176127 The number of permutations of {1,2,...,n,1,2,...,n} with the property that there are k numbers between the two k's in the set for k=1,...,n.

Table of values

List of values