A186560 Number of (n+2)X3 0..2 arrays with every 3X3 subblock commuting with each horizontal and vertical neighbor 3X3 subblock

19683, 721, 2917, 6594, 12122, 20056, 29303, 35198, 53611, 85029, 121783, 199305, 321297, 465750, 728568, 1143162, 1676187, 2600987, 4073323, 6071427, 9378717, 14610267, 21959403, 33776511, 52386811, 79228491, 121620695, 188062383

Offset

1,1

Comments

Column 1 of A186568

Links

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

Formula

Empirical: a(n)=2*a(n-1)-a(n-2)+2*a(n-3)-4*a(n-4)+2*a(n-5)+2*a(n-6)-2*a(n-7) for n>18

Example

Some solutions for 4X3
..1..2..2....0..0..0....0..1..0....0..0..0....0..0..0....1..1..0....1..2..0
..2..2..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..2..0
..0..2..2....2..2..0....2..0..0....2..1..0....0..0..0....0..0..0....0..1..0
..2..1..0....0..2..2....0..2..0....2..1..1....2..0..2....0..1..2....0..0..1

Crossrefs

Sequence in context: A321825 A186559 A186568 * A046322 A224658 A224654

Adjacent sequences: A186557 A186558 A186559 * A186561 A186562 A186563

Keyword

nonn

Author

R. H. Hardin Feb 23 2011

Status

approved