OFFSET
1,1
COMMENTS
Column 1 of A186568
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n)=2*a(n-1)-a(n-2)+2*a(n-3)-4*a(n-4)+2*a(n-5)+2*a(n-6)-2*a(n-7) for n>18
EXAMPLE
Some solutions for 4X3
..1..2..2....0..0..0....0..1..0....0..0..0....0..0..0....1..1..0....1..2..0
..2..2..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..2..0
..0..2..2....2..2..0....2..0..0....2..1..0....0..0..0....0..0..0....0..1..0
..2..1..0....0..2..2....0..2..0....2..1..1....2..0..2....0..1..2....0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Feb 23 2011
STATUS
approved