OFFSET
1,2
EXAMPLE
Some solutions for n=3
..0..1..0....0..1..0....0..1..2....0..0..1....0..1..2....0..1..2....0..1..2
..1..0..1....1..2..1....1..2..1....0..0..2....1..2..0....1..0..0....1..2..1
..0..1..2....0..1..2....2..1..0....1..2..1....2..0..1....2..0..0....2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 29 2012
STATUS
approved