A188450 Number of (2*n)Xn binary arrays with nonzero rows in decreasing order, no more than 3 ones in any row and exactly 2 ones in every column.

0, 1, 8, 66, 722, 9955, 165252, 3221806, 72445292, 1851203574, 53113148720, 1694163830194, 59579694687012

Offset: 1

Author

R. H. Hardin Mar 31 2011

Keywords

• nonn

Comments

Row 2 of A188449

Examples

			Some solutions for 6X3
..1..1..1....1..1..0....1..1..1....1..0..1....1..1..0....1..1..1....1..1..1
..1..0..1....1..0..1....1..0..0....1..0..0....1..0..1....1..0..0....1..1..0
..0..1..0....0..1..0....0..1..1....0..1..1....0..1..1....0..1..0....0..0..1
..0..0..0....0..0..1....0..0..0....0..1..0....0..0..0....0..0..1....0..0..0
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0