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%I #6 Mar 31 2012 12:37:29
%S 5,25,257,6145,262145,25165825,4294967297,1649267441665,
%T 1125899906842625,1729382256910270465,4722366482869645213697,
%U 29014219670751100192948225,316912650057057350374175801345,7788445287802241442795744493830145
%N Half the number of (n+1)X(n+1) 0..2 arrays with every 2X2 subblock having exactly two distinct clockwise edge differences
%C Diagonal of A209534
%H R. H. Hardin, <a href="/A209529/b209529.txt">Table of n, a(n) for n = 1..126</a>
%e Some solutions for n=4
%e ..0..1..2..1..2....0..1..2..1..2....1..0..1..2..1....1..0..1..2..1
%e ..1..0..1..2..1....1..2..1..2..1....0..1..0..1..2....2..1..0..1..2
%e ..2..1..0..1..2....2..1..2..1..0....1..2..1..0..1....1..2..1..2..1
%e ..1..2..1..2..1....1..2..1..2..1....2..1..0..1..2....2..1..2..1..0
%e ..0..1..0..1..2....0..1..2..1..0....1..0..1..2..1....1..2..1..2..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 10 2012