OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) - 4*a(n-4) - 2*a(n-5) - 4*a(n-6).
Empirical g.f.: x*(2 + 2*x - 5*x^3 - 4*x^4 - 4*x^5) / (1 - 2*x - x^2 - 3*x^3 + 4*x^4 + 2*x^5 + 4*x^6). - Colin Barker, Sep 29 2018
EXAMPLE
Some solutions for n=7:
..0..1....0..0....0..0....0..0....0..1....1..0....0..1....0..0....1..1....0..1
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0
..0..1....0..0....0..1....0..0....0..0....0..0....0..0....0..0....0..0....0..0
..0..0....0..0....0..0....1..1....1..1....0..0....0..0....0..0....0..0....0..0
..0..0....0..0....1..0....0..0....0..0....0..1....0..0....1..1....1..0....0..0
..0..0....0..0....0..1....0..0....0..0....0..0....0..0....1..1....0..1....0..1
..0..1....0..1....0..0....0..1....1..1....0..1....1..1....1..1....0..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 09 2013
STATUS
approved