%I #2 Mar 31 2012 12:35:48
%S 1,0,2,17,131,1220,13796,183095,2790353,48045596,922507880,
%T 19543670381,452869998215
%N Number of nX2 arrays containing 2 indistinguishable copies of 1..n with lexicographical ordering of rows strictly increasing and columns strictly decreasing
%C Column 2 of A180843
%e All solutions for 4X2
%e ..1..1....1..1....3..1....2..1....2..1....2..1....2..1....2..1....2..1....2..1
%e ..3..2....3..2....3..2....3..1....3..1....3..1....3..3....3..2....3..2....2..3
%e ..3..4....4..2....4..1....3..2....3..4....4..2....4..1....3..4....4..1....3..1
%e ..4..2....4..3....4..2....4..4....4..2....4..3....4..2....4..1....4..3....4..4
%e ...
%e ..2..1....2..1....2..1....2..1....2..1....2..2....2..2
%e ..2..3....2..3....2..4....2..4....2..4....3..1....3..1
%e ..3..4....4..1....3..1....3..1....3..3....3..4....4..1
%e ..4..1....4..3....4..3....3..4....4..1....4..1....4..3
%K nonn
%O 1,3
%A _R. H. Hardin_ Sep 20 2010