A183304 Half the number of nX3 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

1,2

Comments

Column 3 of A183312

Links

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

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]

Example

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

Crossrefs

Sequence in context: A300438 A034479 A326340 * A359278 A241351 A023377

Adjacent sequences: A183301 A183302 A183303 * A183305 A183306 A183307

Keyword

nonn

Author

R. H. Hardin Jan 03 2011

Status

approved