%I #5 Mar 31 2012 12:36:05
%S 5955,8223,21760,67714,108025,305089,418177,1286113,1812049,5368065,
%T 8100785,22640045,36286649,96020681,161275017,408409609,713044957,
%U 1742523169,3140266657,7453942513,13786320241,31954929709,60372875257
%N Number of (n+1)X7 0..3 arrays with every 2X2 subblock commuting with each of its horizontal and vertical 2X2 subblock neighbors
%C Column 6 of A186482
%H R. H. Hardin, <a href="/A186479/b186479.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>17
%e Some solutions for 3X7
%e ..2..0..0..0..2..0..0....3..1..0..2..0..1..0....1..1..0..2..0..2..0
%e ..3..0..0..0..0..2..0....2..0..1..0..2..0..1....1..0..1..0..2..0..2
%e ..0..3..0..0..0..0..2....0..2..0..1..0..2..0....0..1..0..1..0..2..3
%K nonn
%O 1,1
%A _R. H. Hardin_ Feb 22 2011
|