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) + a(n-3) - a(n-4) for n>6.
Empirical g.f.: x*(49 - 47*x + 6*x^2 - 45*x^3 + 4*x^4 + x^5) / ((1 - x)*(1 - x - x^3)). - Colin Barker, Dec 21 2018
EXAMPLE
Some solutions for n=4:
..0..0..0..0..0..0....0..1..1..0..1..1....1..1..0..1..1..1....0..0..0..0..0..0
..1..1..0..1..1..0....0..0..0..0..0..0....1..1..0..1..1..1....1..1..0..1..1..0
..1..1..0..1..1..0....0..1..1..0..1..1....0..0..0..0..0..0....1..1..0..1..1..0
..1..1..0..1..1..0....0..1..1..0..1..1....1..1..0..1..1..1....1..1..0..1..1..0
..0..0..0..0..0..0....0..1..1..0..1..1....1..1..0..1..1..1....1..1..0..1..1..0
..1..1..0..1..1..0....0..0..0..0..0..0....0..0..0..0..0..0....1..1..0..1..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 23 2015
STATUS
approved