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%I #5 Aug 12 2016 07:04:21
%S 1,1,11,234,8466,465690,36290610,3806425980,517149634680,
%T 88352470838520,18539220178017000,4687139017126566000
%N Number of nX2 arrays containing 2 copies of 0..n-1 with no element 1 greater than its northeast neighbor modulo n and the upper left element equal to 0.
%C Column 2 of A266655.
%e Some solutions for n=4
%e ..0..1....0..1....0..0....0..3....0..3....0..2....0..3....0..1....0..3....0..1
%e ..3..2....0..1....2..1....2..3....1..0....1..3....3..2....3..0....2..1....1..2
%e ..0..1....3..2....3..3....2..1....2..3....2..1....1..2....2..3....1..0....2..0
%e ..3..2....2..3....2..1....0..1....1..2....0..3....1..0....2..1....2..3....3..3
%Y Cf. A266655.
%K nonn
%O 1,3
%A _R. H. Hardin_, Jan 02 2016