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.

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

Offset: 1

Author

R. H. Hardin Jul 04 2013

Keywords

• nonn

Comments

Diagonal of A227263

Examples

			Some solutions for n=4
..1..1..1..0....1..1..1..1....1..1..1..1....1..1..1..0....1..1..0..0
..1..0..0..1....1..0..1..1....1..0..1..1....1..0..0..0....1..1..1..0
..0..1..1..1....1..1..0..1....1..1..1..0....1..0..0..1....1..1..1..1
..0..0..1..1....1..1..0..0....0..1..0..0....0..0..0..1....0..1..1..1