A231213 Number of (n+1) X (2+1) 0..2 arrays with no element unequal to a strict majority of its horizontal and vertical neighbors, with values 0..2 introduced in row major order.

4, 9, 22, 59, 156, 413, 1098, 2919, 7760, 20633, 54862, 145875, 387876, 1031349, 2742322, 7291743, 19388504, 51553393, 137078774, 364487947, 969161452, 2576968397, 6852074138, 18219439575, 48444890080, 128813368009, 342510505246

Offset: 1

Author

R. H. Hardin, Nov 05 2013

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 2 of A231219.

Formula

Empirical: a(n) = 3*a(n-1) - a(n-2) + a(n-3) - 2*a(n-4).

Empirical g.f.: x*(4 - 3*x - x^2 - 2*x^3) / ((1 - x)*(1 - 2*x - x^2 - 2*x^3)). - Colin Barker, Sep 27 2018