OFFSET
1,2
EXAMPLE
Some solutions for n=4:
.-1...-4...-3...-1...-3...-3...-2...-3...-3...-4...-3...-3...-4...-2...-2...-2
.-1....0....1....1....1....2....0....0....0....1...-1...-1....1...-2....0....2
.-1....3....1...-1...-1...-2...-2...-1....0....1....0....2....0....0...-1...-2
..3....1....1....1....3....3....4....4....3....2....4....2....3....4....3....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
EXTENSIONS
a(10)-a(20) from Andrew Howroyd, Mar 02 2017
STATUS
approved