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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A363181 Number of permutations p of [n] such that for each i in [n] we have: (i>1) and |p(i)-p(i-1)| = 1 or (i and |p(i)-p(i+1)| = 1.

Table of values

n a(n)
0 1
1 0
2 2
3 2
4 8
5 14
6 54
7 128
8 498
9 1426
10 5736
11 18814
12 78886
13 287296
14 1258018
15 4986402
16 22789000
17 96966318
18 461790998
19 2088374592
20 10343408786
21 49343711666
22 253644381032
23 1268995609502
24 6756470362374
25 35285321738624
26 194220286045506
27 1054759508543554

List of values

[1, 0, 2, 2, 8, 14, 54, 128, 498, 1426, 5736, 18814, 78886, 287296, 1258018, 4986402, 22789000, 96966318, 461790998, 2088374592, 10343408786, 49343711666, 253644381032, 1268995609502, 6756470362374, 35285321738624, 194220286045506, 1054759508543554]

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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