OFFSET
1,2
COMMENTS
Column 4 of A216031
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..20
EXAMPLE
Some solutions for n=4
..x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..1
..1..x..2..x....2..x..1..x....0..x..2..x....0..x..1..x....2..x..1..x
..x..2..x..3....x..3..x..2....x..1..x..0....x..1..x..2....x..1..x..3
..3..x..4..x....1..x..4..x....3..x..4..x....1..x..3..x....1..x..3..x
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Aug 30 2012
STATUS
approved