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

1,1

Links

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

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

Example

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

Crossrefs

Column 2 of A231219.

Sequence in context: A318817 A122626 A135025 * A231338 A257272 A370021

Adjacent sequences: A231210 A231211 A231212 * A231214 A231215 A231216

Keyword

nonn

Author

R. H. Hardin, Nov 05 2013

Status

approved