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

1,1

Comments

Column 3 of A228660

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

Example

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

Crossrefs

Sequence in context: A117616 A345757 A369836 * A192402 A014445 A113440

Adjacent sequences: A228652 A228653 A228654 * A228656 A228657 A228658

Keyword

nonn

Author

R. H. Hardin Aug 29 2013

Status

approved