OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 5*a(n-1) - 8*a(n-2) + a(n-3) + 9*a(n-4) - 6*a(n-5) - 6*a(n-7) + 9*a(n-8) + a(n-9) - 8*a(n-10) + 5*a(n-11) - a(n-12).
Empirical g.f.: x*(4 - 6*x + x^2 + 9*x^3 - 6*x^4 - 6*x^6 + 9*x^7 + x^8 - 8*x^9 + 5*x^10 - x^11) / ((1 - x)^8*(1 + x)^2*(1 + x + x^2)). - Colin Barker, Jan 09 2019
EXAMPLE
Some solutions for n=4:
..0..0..1....0..0..1....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1
..0..0..1....0..1..1....0..0..0....0..0..1....0..1..1....0..0..0....0..1..1
..1..1..0....1..1..0....0..0..1....0..1..1....0..1..1....0..0..0....1..1..1
..1..1..0....1..1..1....1..1..1....0..1..1....0..1..1....1..1..1....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 29 2015
STATUS
approved