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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.

A032351 Number of permutations of length n which avoid the patterns 2143, 1324 (smooth permutations); or avoid the patterns 1342, 2431; etc.

Table of values

n a(n)
0 1
1 1
2 2
3 6
4 22
5 88
6 366
7 1552
8 6652
9 28696
10 124310
11 540040
12 2350820
13 10248248
14 44725516
15 195354368
16 853829272
17 3733693872
18 16333556838
19 71476391800
20 312865382004
21 1369760107576
22 5998008630244
23 26268304208032
24 115055864102504
25 503997820344464
26 2207927106851580
27 9673223726469136
28 42382192892577128
29 185702341264971696

List of values

[1, 1, 2, 6, 22, 88, 366, 1552, 6652, 28696, 124310, 540040, 2350820, 10248248, 44725516, 195354368, 853829272, 3733693872, 16333556838, 71476391800, 312865382004, 1369760107576, 5998008630244, 26268304208032, 115055864102504, 503997820344464, 2207927106851580, 9673223726469136, 42382192892577128, 185702341264971696]

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

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