%I #7 Dec 11 2015 21:30:14

%S 256,19688,3802676,5674969344,51975660472496,2363371012699739212

%N Number of (n+1) X (n+1) 0..3 arrays with every 2 X 2 subblock having the same number of clockwise edge increases as its horizontal neighbors and the same number of counterclockwise edge increases as its vertical neighbors.

%C Diagonal of A206188.

%e Some solutions for n=4:

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 04 2012