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%I #7 Dec 11 2015 11:58:32
%S 256,33688,8114696,12793359564,115868265653308,5228849998045900208,
%T 1142673565861296088168308
%N Number of (n+1) X (n+1) 0..3 arrays with the number of clockwise edge increases in 2 X 2 subblocks nondecreasing, and counterclockwise edge increases nonincreasing, rightwards and downwards.
%C Diagonal of A206109.
%e Some solutions for n=4:
%e ..0..2..3..1..2....1..3..1..2..2....1..2..2..3..1....1..3..0..1..0
%e ..2..2..3..3..3....3..2..0..1..3....1..2..3..3..3....1..3..0..0..0
%e ..3..2..2..2..0....2..3..2..0..0....1..2..2..2..2....1..3..3..3..3
%e ..2..2..1..1..1....0..2..0..3..1....1..1..1..2..3....1..1..3..1..1
%e ..2..1..1..3..2....2..1..3..2..1....0..0..0..2..0....2..1..3..3..1
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 03 2012
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