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.

A174637 Number of n X n (0,1) matrices with two 1's in each row the permanent of which equals to 4.

Table of values

n a(n)
1 0
2 0
3 0
4 18
5 2400
6 325800
7 52496640
8 10304300160
9 2458401684480
10 705918026419200
11 241147866161664000
12 96890287539173990400
13 45304089884519168102400
14 24415719893124157985587200
15 15035096121857624246353920000
16 10496828397482345253454479360000
17 8250414679239607850470753370112000

List of values

[0, 0, 0, 18, 2400, 325800, 52496640, 10304300160, 2458401684480, 705918026419200, 241147866161664000, 96890287539173990400, 45304089884519168102400, 24415719893124157985587200, 15035096121857624246353920000, 10496828397482345253454479360000, 8250414679239607850470753370112000]

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

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