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

1,2

Comments

Diagonal of A202979

Links

Table of n, a(n) for n=1..13.

Example

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

Crossrefs

Sequence in context: A128159 A319591 A198405 * A085617 A152557 A015202

Adjacent sequences: A202969 A202970 A202971 * A202973 A202974 A202975

Keyword

nonn

Author

R. H. Hardin Dec 26 2011

Status

approved