A228655 Number of nX3 binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally.

2, 8, 34, 140, 574, 2348, 9598, 39224, 160282, 654944, 2676202, 10935332, 44683222, 182581508, 746051878, 3048465200, 12456425842, 50898577976, 207978216754, 849826072316, 3472499977390, 14189087019740, 57978456949582

Offset: 1

Author

R. H. Hardin Aug 29 2013

Keywords

• nonn

Comments

Column 3 of A228660

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 5*a(n-1) -3*a(n-2) -3*a(n-3).

Empirical: G.f. -2*x*(-1+x) / ( 1-5*x+3*x^2+3*x^3 ). - R. J. Mathar, Aug 29 2013