A384921 - cp's OEIS frontend

A384921 Number of permutations [p_1, p_2, ..., p_n], for n >= 1, with |p_{i+1} - p_i| >= 2, for i = 1..n-1, and |p_n - p_1| = 0 or 1.

n	a(n)
1	1
2	0
3	0
4	2
5	4
6	30
7	184
8	1322
9	10668
10	96566
11	969280
12	10690146
13	128527348
14	1673257262
15	23451539784
16	352079626010
17	5637207651004
18	95886993887142
19	1726775043225808
20	32821564079286866
21	656647922936247300
22	13793480376190668446

[1, 0, 0, 2, 4, 30, 184, 1322, 10668, 96566, 969280, 10690146, 128527348, 1673257262, 23451539784, 352079626010, 5637207651004, 95886993887142, 1726775043225808, 32821564079286866, 656647922936247300, 13793480376190668446]

cp's OEIS Frontend

A384921 Number of permutations [p_1, p_2, ..., p_n], for n >= 1, with |p_{i+1} - p_i| >= 2, for i = 1..n-1, and |p_n - p_1| = 0 or 1.

Table of values

List of values