OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..78
EXAMPLE
Some solutions for n=4:
..0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x
..x..2..x..1....x..0..x..1....x..2..x..0....x..2..x..3....x..2..x..0
..1..x..2..x....2..x..3..x....0..x..3..x....3..x..4..x....0..x..3..x
..x..1..x..2....x..0..x..1....x..0..x..3....x..5..x..3....x..1..x..4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 04 2012
STATUS
approved