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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.

A239368 Number of words of length n over the alphabet {0,...,n-1} that avoid the pattern 1111.

Table of values

n a(n)
0 1
1 1
2 4
3 27
4 252
5 3020
6 44220
7 765030
8 15269520
9 345376080
10 8730489600
11 243911883600
12 7463164262400
13 248207881521600
14 8915064168410400
15 343923449355486000
16 14182674669779616000
17 622591172035376544000
18 28986699477880400256000
19 1426677017904959524704000

List of values

[1, 1, 4, 27, 252, 3020, 44220, 765030, 15269520, 345376080, 8730489600, 243911883600, 7463164262400, 248207881521600, 8915064168410400, 343923449355486000, 14182674669779616000, 622591172035376544000, 28986699477880400256000, 1426677017904959524704000]

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

Content is available under The OEIS End-User License Agreement.