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%I #5 Mar 31 2012 12:37:30
%S 64,12492,13606964,89046135210,3413352967754696,774627496109684203370,
%T 1034141529418861531701953000,8145663030420623706384712975053986
%N Half the number of (n+1)X(n+1) 0..3 arrays with every 2X2 subblock having exactly one duplicate clockwise edge difference
%C Diagonal of A209787
%e Some solutions for n=4
%e ..0..3..3..3..2....3..0..1..0..0....3..3..0..3..1....0..3..1..3..0
%e ..2..1..1..1..1....3..0..1..1..2....1..3..3..3..1....2..1..1..3..3
%e ..0..3..2..1..2....0..0..0..0..0....1..1..3..2..1....3..3..2..2..1
%e ..3..3..1..1..2....0..3..0..1..1....3..1..1..2..1....3..2..2..1..1
%e ..2..1..1..2..2....2..1..2..2..1....3..2..0..2..0....3..3..1..1..2
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 13 2012
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