OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 5*a(n-1) - a(n-2) - a(n-3) + 4*a(n-4) - 4*a(n-5) - 3*a(n-6) + a(n-7).
Empirical g.f.: x*(1 + x)^2*(1 - 3*x + 6*x^2 - 7*x^3 + 2*x^4) / ((1 - x)*(1 - 4*x - 3*x^2 - 2*x^3 - 6*x^4 - 2*x^5 + x^6)). - Colin Barker, Oct 29 2018
EXAMPLE
Some solutions for n=4:
..0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0....0..1..0
..0..1..1....1..0..1....0..1..0....0..1..0....0..1..0....1..0..1....1..1..0
..0..1..1....0..1..1....1..0..1....1..1..0....0..0..1....1..1..0....1..0..0
..0..1..0....0..1..0....0..1..0....1..1..0....1..0..1....0..1..0....1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2014
STATUS
approved