A281049 Number of n X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 1, 68, 1022, 7803, 46610, 221212, 926077, 3549039, 12749511, 43675963, 144504080, 466130380

Offset: 1

Author

R. H. Hardin, Jan 13 2017

Keywords

• nonn

Comments

Diagonal of A281056.

Examples

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

Crossrefs

Cf. A281056.