A186481 - OEIS

%I #5 Mar 31 2012 12:36:05

%S 27101,35081,101108,286290,479785,1286113,1894849,5977657,8078233,

%T 25049545,34600393,103930809,154520201,437740901,693356465,1854858401,

%U 3085313121,7883094433,13654582357,33612555865,60183013369,143706271561

%N Number of (n+1)X9 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors

%C Column 8 of A186482

%H R. H. Hardin, <a href="/A186481/b186481.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n)=2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-4)-3*a(n-5) for n>19

%e Some solutions for 3X9

%e ..1..0..3..0..1..0..1..0..1....2..2..0..2..0..1..0..0..0

%e ..0..1..0..3..0..1..0..1..0....2..0..2..0..2..0..1..0..0

%e ..2..0..1..0..3..0..1..0..1....0..2..0..2..0..2..0..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_ Feb 22 2011