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%I #5 Aug 12 2016 07:04:22
%S 1,0,4,23,398,23432,1841274,193070360,26165335486,4456558300940,
%T 932617500467182
%N Number of nX2 arrays containing 2 copies of 0..n-1 with no element 1 greater than its north, southwest or southeast neighbor modulo n and the upper left element equal to 0.
%C Column 2 of A266921.
%e Some solutions for n=6
%e ..0..1....0..2....0..0....0..3....0..3....0..5....0..2....0..5....0..5....0..4
%e ..4..1....5..0....2..4....4..1....4..2....2..3....5..2....3..2....3..1....2..3
%e ..2..0....3..5....2..3....3..5....3..1....0..3....4..1....5..1....2..4....5..3
%e ..4..3....3..1....4..5....2..1....1..5....4..1....3..4....4..0....2..4....1..5
%e ..3..5....2..1....3..1....4..5....5..2....2..1....1..0....4..2....5..3....0..2
%e ..2..5....4..4....1..5....0..2....4..0....5..4....3..5....3..1....1..0....4..1
%Y Cf. A266921.
%K nonn
%O 1,3
%A _R. H. Hardin_, Jan 06 2016