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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.

A177470 Number of permutations of order n avoiding the consecutive pattern 11'22'.

Table of values

n a(n)
0 1
1 1
2 2
3 6
4 18
5 70
6 300
7 1435
8 7910
9 47376
10 316008
11 2314158
12 18331236
13 158024724
14 1462752720
15 14497475850
16 153488070450
17 1724035906450
18 20515906356660
19 257720354712106
20 3406481187714176
21 47293781230517640
22 687760952277462336
23 10456003715906638162
24 165890170459303164420

List of values

[1, 1, 2, 6, 18, 70, 300, 1435, 7910, 47376, 316008, 2314158, 18331236, 158024724, 1462752720, 14497475850, 153488070450, 1724035906450, 20515906356660, 257720354712106, 3406481187714176, 47293781230517640, 687760952277462336, 10456003715906638162, 165890170459303164420]

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

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