A202972 Number of n X n 0..1 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors.

1, 2, 17, 385, 31380, 8071997, 6330398606, 15305115754880, 113359928263133320, 2565928235760939767164, 177686302889022383527488349, 37653160193950657089306550224687, 24413727008012244865702150476410950284

Offset: 1

Author

R. H. Hardin Dec 26 2011

Keywords

• nonn

Comments

Diagonal of A202979

Examples

			Some solutions for n=5
..0..0..1..1..0....1..1..1..1..1....0..1..1..1..0....1..1..1..0..0
..0..0..1..1..0....1..1..0..1..1....1..1..0..1..0....1..0..1..1..0
..1..1..1..0..0....1..1..0..1..0....1..1..1..1..1....1..1..1..1..1
..1..1..1..1..1....0..0..0..1..1....1..1..1..0..1....0..1..1..1..1
..1..1..0..1..1....0..0..0..1..1....0..0..1..1..1....0..1..1..0..0