OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) - 2*a(n-3) +a(n-4).
Empirical g.f.: x*(10 - 6*x - 7*x^2 + 4*x^3) / ((1 - x)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Nov 15 2018
EXAMPLE
Some solutions for n=6:
..0..0....1..1....1..1....0..1....0..0....1..1....0..0....0..0....0..0....1..1
..1..1....0..1....0..1....1..1....1..1....0..1....0..0....0..0....0..0....0..1
..1..1....1..0....0..1....1..1....1..1....1..1....1..1....1..0....0..0....0..1
..0..1....0..1....1..1....0..1....1..1....0..1....0..1....0..1....1..1....1..1
..0..1....1..0....1..1....0..1....0..1....0..1....1..0....1..1....1..1....1..1
..0..1....0..1....0..1....1..1....1..0....0..1....0..1....1..1....0..1....1..1
..1..1....1..0....1..0....1..1....0..1....1..0....1..1....0..1....1..0....0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 25 2014
STATUS
approved