A180189 - cp's OEIS frontend

A180189 Number of permutations of [n] having exactly 1 circular succession. A circular succession in a permutation p of [n] is either a pair p(i), p(i+1), where p(i+1)=p(i)+1 or the pair p(n), p(1) if p(1)=p(n)+1.

n	a(n)
1	0
2	2
3	0
4	12
5	40
6	270
7	1848
8	14840
9	133488
10	1334970
11	14684560
12	176214852
13	2290792920
14	32071101062
15	481066515720
16	7697064251760
17	130850092279648
18	2355301661033970
19	44750731559645088
20	895014631192902140
21	18795307255050944520
22	413496759611120779902

[0, 2, 0, 12, 40, 270, 1848, 14840, 133488, 1334970, 14684560, 176214852, 2290792920, 32071101062, 481066515720, 7697064251760, 130850092279648, 2355301661033970, 44750731559645088, 895014631192902140, 18795307255050944520, 413496759611120779902]

cp's OEIS Frontend

A180189 Number of permutations of [n] having exactly 1 circular succession. A circular succession in a permutation p of [n] is either a pair p(i), p(i+1), where p(i+1)=p(i)+1 or the pair p(n), p(1) if p(1)=p(n)+1.

Table of values

List of values