OFFSET
1,2
EXAMPLE
Some solutions for n=4
..0........0........0........0........0........0........0........0
..1.2......1.2......1.1......1.2......1.2......1.2......0.1......0.1
..1.2.1....3.3.4....2.3.4....0.3.0....0.3.3....3.2.3....0.2.2....2.3.4
..3.2.4.0..4.5.1.2..5.3.6.0..2.1.1.3..4.5.6.7..3.1.4.0..0.3.0.1..2.5.0.6
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Apr 26 2012
STATUS
approved