cp's OEIS Frontend

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.

A258664 A total of n married couples, including a mathematician M and his wife, are to be seated at the 2n chairs around a circular table, with no man seated next to his wife. After the ladies are seated at every other chair, M is the first man allowed to choose one of the remaining chairs. The sequence gives the number of ways of seating the other men, with no man seated next to his wife, if M chooses the chair that is 3 seats clockwise from his wife's chair.

Table of values

n a(n)
1 0
2 0
3 1
4 1
5 4
6 20
7 115
8 787
9 6184
10 54888
11 542805
12 5916725
13 70463900
14 910167596
15 12672415015
16 189181881575
17 3014307220880
18 51054940726928
19 915987174021609
20 17352888926841897
21 346144782915314740
22 7251738265074465220
23 159193007549552845339
24 3654204694819144118651

List of values

[0, 0, 1, 1, 4, 20, 115, 787, 6184, 54888, 542805, 5916725, 70463900, 910167596, 12672415015, 189181881575, 3014307220880, 51054940726928, 915987174021609, 17352888926841897, 346144782915314740, 7251738265074465220, 159193007549552845339, 3654204694819144118651]

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

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