

A186560


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


1



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
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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(n1)a(n2)+2*a(n3)4*a(n4)+2*a(n5)+2*a(n6)2*a(n7) 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



