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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.

A382411 a(n) is the greatest possible length of a circular sequence on n symbols such that: no two adjacent symbols are the same, any group of n adjacent symbols contains at least n-1 different symbols, and all groups of n adjacent symbols within the sequence are unique.

Table of values

n a(n)
1 1
2 2
3 12
4 96
5 840
6 7920
7 80640
8 887040
9 10523520
10 134265600
11 1836172800
12 26824089600
13 417210393600
14 6887085004800
15 120306041856000
16 2217815728128000
17 43038178799616000
18 877125197684736000
19 18733345462960128000
20 418459145406382080000
21 9758369954796503040000
22 237164153561075220480000

List of values

[1, 2, 12, 96, 840, 7920, 80640, 887040, 10523520, 134265600, 1836172800, 26824089600, 417210393600, 6887085004800, 120306041856000, 2217815728128000, 43038178799616000, 877125197684736000, 18733345462960128000, 418459145406382080000, 9758369954796503040000, 237164153561075220480000]

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

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