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%I #7 Dec 10 2015 02:00:24
%S 104,7688,1763560,1312173688,3222294559864,26463715503890184,
%T 732416961112609324840,68720985559450744063171672
%N Number of (n+1) X (n+1) 0..3 arrays with the number of clockwise edge increases in every 2 X 2 subblock unequal to the number of counterclockwise edge increases.
%C Diagonal of A206021.
%e Some solutions for n=3:
%e ..2..2..3..0....3..1..3..1....1..1..3..2....3..0..1..0....1..1..3..3
%e ..3..0..3..1....0..0..3..0....0..2..3..0....1..0..2..2....3..2..2..0
%e ..3..1..2..1....2..1..3..2....1..1..3..2....1..3..3..0....3..0..1..1
%e ..0..1..0..1....2..0..3..0....2..0..0..1....0..0..2..1....1..0..2..3
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 02 2012