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.

A227258 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 two or less, with rows and columns of the latter in lexicographically nondecreasing order.

Table of values

n a(n)
1 2
2 9
3 98
4 2201
5 112349
6 13855163
7 4307345460

List of values

[2, 9, 98, 2201, 112349, 13855163, 4307345460]

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

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