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%I #7 Oct 09 2015 04:29:32
%S 256,28724,8381936,11786800328,101664965477840,4561749663096542724,
%T 995980221935339574016820
%N Number of (n+1)X(n+1) 0..3 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.
%C Diagonal of A205642.
%e Some solutions for n=4:
%e ..0..0..2..2..3....2..0..0..0..2....3..3..1..3..1....2..1..1..2..1
%e ..0..2..2..3..3....1..2..1..2..1....1..0..0..0..0....0..0..2..2..1
%e ..2..2..3..3..0....3..2..0..1..0....1..2..1..3..1....3..2..2..0..0
%e ..2..3..3..0..0....3..0..1..3..1....3..2..0..3..3....3..3..2..3..1
%e ..2..3..0..0..2....2..3..0..1..2....3..1..0..3..0....3..0..2..0..0
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 29 2012