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.

A239840 Number of ordered pairs of permutation functions (f,g) on n elements satisfying f(x) = f(g(g(x))).

Table of values

n a(n)
0 1
1 1
2 4
3 24
4 240
5 3120
6 54720
7 1169280
8 30804480
9 950745600
10 34459084800
11 1424870092800
12 67133032243200
13 3540086232883200
14 208397961547776000
15 13533822947893248000
16 966773828738285568000
17 75334352557782269952000
18 6385175803136642383872000

List of values

[1, 1, 4, 24, 240, 3120, 54720, 1169280, 30804480, 950745600, 34459084800, 1424870092800, 67133032243200, 3540086232883200, 208397961547776000, 13533822947893248000, 966773828738285568000, 75334352557782269952000, 6385175803136642383872000]

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

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