OFFSET
1,1
COMMENTS
Column 3 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>11.
Empirical g.f.: x*(2917 - 5433*x + 3514*x^2 - 4810*x^3 + 10230*x^4 - 7616*x^5 - 7774*x^6 + 6916*x^7 + 1280*x^8 - 288*x^9 + 800*x^10) / ((1 - x)*(1 - x - 2*x^3 + 2*x^4 - 2*x^6)). - Colin Barker, Apr 18 2018
EXAMPLE
Some solutions for 4 X 5:
..0..0..0..0..1....0..0..0..0..0....0..0..0..0..2....0..0..0..0..2
..0..0..0..0..1....0..0..0..0..0....0..0..0..0..2....0..0..0..0..0
..1..0..0..0..1....0..0..0..0..0....0..0..0..0..2....0..0..0..0..0
..1..0..0..0..1....1..1..1..1..1....1..0..0..0..2....2..2..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 23 2011
STATUS
approved