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.

A216675 Number of ways one can draw arrows between adjacent nodes of an n X n grid such that each node has one outgoing and one incoming arrow.

Table of values

n a(n)
1 0
2 4
3 0
4 1296
5 0
6 45265984
7 0
8 168709341081856
9 0
10 66865709036047973991424
11 0
12 2815414274858422422282241600000000
13 0
14 12589335654221209921194197564847684000000000000
15 0
16 5977481098898922857923760209743284068237948337696882106105856
17 0

List of values

[0, 4, 0, 1296, 0, 45265984, 0, 168709341081856, 0, 66865709036047973991424, 0, 2815414274858422422282241600000000, 0, 12589335654221209921194197564847684000000000000, 0, 5977481098898922857923760209743284068237948337696882106105856, 0]

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

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