OFFSET
1,1
COMMENTS
Column 1 of A186881
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n)=2*a(n-1)-a(n-2)+3*a(n-3)-6*a(n-4)+3*a(n-5)+3*a(n-6)-3*a(n-7) for n>20
EXAMPLE
Some solutions for 4X3
..3..3..0....1..0..1....0..3..0....2..0..0....0..0..0....2..0..0....0..0..0
..0..3..3....2..0..0....0..0..0....0..0..2....0..0..0....0..2..0....0..0..0
..0..3..0....0..2..0....0..0..0....0..0..2....1..1..0....0..0..2....2..3..0
..0..0..3....0..0..2....0..2..2....0..0..2....2..3..1....2..1..3....0..0..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Feb 28 2011
STATUS
approved