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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.

A227381 Number of n X n 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(n+1) binary array having a sum of one, with rows and columns of the latter in lexicographically nondecreasing order.

Table of values

n a(n)
1 2
2 7
3 54
4 1104
5 61127
6 8988949
7 3657501287

List of values

[2, 7, 54, 1104, 61127, 8988949, 3657501287]

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

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