A268621 Number of n X n 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totaling two no more than once.

3, 42, 1086, 55452, 6000978, 1430057208, 767057092212, 938662461734076, 2643885168776274078, 17245474696462104041796, 261641272761781630830646332, 9262823664147270920479995625968, 767111588793900754143144516979246884

Offset: 1

Author

R. H. Hardin, Feb 09 2016

Keywords

• nonn

Comments

Diagonal of A268628.

Examples

			Some solutions for n=4
..2..1..2..2. .0..0..0..0. .0..0..1..0. .2..1..0..0. .1..1..0..0
..1..0..1..2. .0..1..1..0. .0..0..0..1. .1..0..0..0. .2..2..1..0
..2..1..2..1. .1..0..0..1. .1..0..1..2. .0..1..0..0. .2..2..2..1
..2..2..2..0. .0..0..1..0. .0..1..2..2. .0..0..0..1. .2..2..1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..14

Crossrefs

Cf. A268628.