A183304 Half the number of n X 3 binary arrays with no element equal to a strict majority of its horizontal and vertical neighbors.

1, 4, 9, 19, 42, 93, 205, 452, 997, 2199, 4850, 10697, 23593, 52036, 114769, 253131, 558298, 1231365, 2715861, 5990020, 13211405, 29138671, 64267362, 141746129, 312630929, 689529220, 1520804569, 3354240067, 7398009354, 16316823277

Offset: 1

Author

R. H. Hardin, Jan 03 2011

Keywords

• nonn

Examples

			Some solutions with a(1,1)=0 for 3X4
..0..1..0..1....0..0..1..1....0..1..0..1....0..1..0..0....0..1..1..0
..1..0..0..1....1..1..0..0....0..1..1..0....1..0..1..1....1..0..0..1
..0..1..1..0....0..1..0..1....1..0..1..0....0..1..0..0....0..1..1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Column 3 of A183312.

Formula

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

Empirical G.f.: x*(1+x)^2/(1-2*x-x^3). - Colin Barker, Feb 23 2012