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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.

A145868 Number of involutions of length 2n+1 which are invariant under the reverse-complement map and have no decreasing subsequences of length 7.

Table of values

n a(n)
0 1
1 2
2 6
3 19
4 68
5 255
6 1020
7 4221
8 18186
9 80304
10 364476
11 1684782
12 7944156
13 37988379
14 184406508
15 905147815
16 4495346570
17 22527055980
18 113957354940
19 580759868910
20 2982724210440
21 15414453711930
22 80177422383240
23 419249099692710
24 2204316120027420
25 11642676960438000

List of values

[1, 2, 6, 19, 68, 255, 1020, 4221, 18186, 80304, 364476, 1684782, 7944156, 37988379, 184406508, 905147815, 4495346570, 22527055980, 113957354940, 580759868910, 2982724210440, 15414453711930, 80177422383240, 419249099692710, 2204316120027420, 11642676960438000]

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

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