cp's OEIS Frontend

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.

A239076 Number of self-inverse permutations p on [n] with displacement of elements restricted by 4: |p(i)-i| <= 4.

Table of values

n a(n)
0 1
1 1
2 2
3 4
4 10
5 26
6 66
7 158
8 376
9 891
10 2137
11 5140
12 12376
13 29756
14 71468
15 171596
16 412084
17 989800
18 2377717
19 5711705
20 13720054
21 32955996
22 79161006
23 190147558
24 456743814
25 1097123162
26 2635347280
27 6330234855
28 15205529809
29 36524416280
30 87733426944
31 210739993784

List of values

[1, 1, 2, 4, 10, 26, 66, 158, 376, 891, 2137, 5140, 12376, 29756, 71468, 171596, 412084, 989800, 2377717, 5711705, 13720054, 32955996, 79161006, 190147558, 456743814, 1097123162, 2635347280, 6330234855, 15205529809, 36524416280, 87733426944, 210739993784]

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

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