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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.

A229165 a(n) is the number of n X n matrices of 0's, 1's and -1's in which the entries in each row or column sum to 1 and there are no adjacent -1's or 1's in any row or column.

Table of values

n a(n)
1 1
2 2
3 7
4 104
5 7255
6 2280064
7 2708080414
8 13039886441460

List of values

[1, 2, 7, 104, 7255, 2280064, 2708080414, 13039886441460]

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

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