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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.

A364819 Number of permutations p of [n] such that max(|p(p(i)) - i|)=1.

Table of values

n a(n)
2 0
3 0
4 2
5 6
6 24
7 80
8 312
9 1152
10 4616
11 18384
12 77280
13 328352
14 1451712
15 6527616
16 30299504
17 143322000
18 696359232
19 3448656512
20 17483842176
21 90301959744
22 476270369600
23 2557007766912
24 13991998520832
25 77867819879936
26 441003737739264
27 2537848321044480
28 14843836828748672

List of values

[0, 0, 2, 6, 24, 80, 312, 1152, 4616, 18384, 77280, 328352, 1451712, 6527616, 30299504, 143322000, 696359232, 3448656512, 17483842176, 90301959744, 476270369600, 2557007766912, 13991998520832, 77867819879936, 441003737739264, 2537848321044480, 14843836828748672]

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

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