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%I #7 Dec 10 2015 02:14:53
%S 81,1791,87918,14150391,6011669886,6566654061039,18225426305218983,
%T 128865421969802643036,2315569396435124102371935
%N Number of (n+1) X (n+1) 0..2 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 A205917.
%e Some solutions for n=4:
%e ..1..0..2..2..0....1..0..0..1..2....2..2..2..0..1....2..1..0..1..0
%e ..0..0..0..0..0....0..2..1..0..2....0..2..0..0..0....2..1..1..1..1
%e ..0..1..1..1..0....0..1..1..2..2....2..2..0..2..2....1..1..2..1..2
%e ..0..0..1..0..0....1..0..2..1..0....0..2..2..2..0....0..1..1..1..1
%e ..0..1..1..0..2....1..2..2..0..0....2..2..0..0..0....0..1..0..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 01 2012