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.

A201996 The number of endofunctions on n points such that all recurrent elements have at most 3 preimages and all nonrecurrent elements have at most 2 preimages.

Table of values

n a(n)
0 1
1 1
2 4
3 27
4 252
5 3000
6 43380
7 737730
8 14419440
9 318381840
10 7835486400
11 212634298800
12 6307073942400
13 202983948367200
14 7044249755743200
15 262198957638618000
16 10419369722457696000
17 440257835691561888000
18 19709455059507717504000
19 931885122471464345184000
20 46401644730376725229440000

List of values

[1, 1, 4, 27, 252, 3000, 43380, 737730, 14419440, 318381840, 7835486400, 212634298800, 6307073942400, 202983948367200, 7044249755743200, 262198957638618000, 10419369722457696000, 440257835691561888000, 19709455059507717504000, 931885122471464345184000, 46401644730376725229440000]

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

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