OFFSET
1,3
EXAMPLE
Some solutions for n=4
..3..3..1..1....2..2..3..0....2..2..1..1....2..2..3..0....3..3..0..0
..3..3..0..2....2..2..3..0....2..0..0..1....2..3..3..0....3..1..1..1
..1..0..0..2....3..3..3..1....1..0..2..2....3..3..3..0....0..1..1..0
..1..2..2..2....0..0..1..1....1..1..2..2....0..0..0..0....0..1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 31 2012
STATUS
approved