OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4).
Empirical g.f.: x*(10 - 5*x + 6*x^2 - 4*x^3) / (1 - 3*x + 2*x^2 - 2*x^3 + x^4). - Colin Barker, Nov 28 2018
EXAMPLE
Some solutions for n=4:
..1..1....1..1....1..0....0..0....1..0....0..1....0..1....0..1....1..0....0..1
..0..1....0..0....1..0....0..0....1..0....0..1....0..0....0..1....1..0....0..0
..0..1....0..0....1..1....1..1....1..1....0..0....1..1....0..0....1..0....1..1
..1..0....1..0....0..0....0..1....0..1....1..1....0..1....1..0....1..1....0..1
..1..1....1..1....1..0....0..1....0..0....0..0....1..0....1..0....0..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 01 2014
STATUS
approved