OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) + 9*a(n-2) - 6*a(n-3) - 2*a(n-4).
Empirical g.f.: x*(59 + 73*x - 56*x^2 - 18*x^3) / (1 - 6*x - 9*x^2 + 6*x^3 + 2*x^4). - Colin Barker, Oct 17 2018
EXAMPLE
Some solutions for n=5:
..1..1....0..0....1..1....0..1....0..0....0..0....1..0....0..0....0..0....1..2
..1..2....2..1....2..0....1..2....0..0....1..2....0..0....2..1....1..1....1..0
..1..0....2..1....2..1....0..1....0..1....1..1....1..0....0..1....0..1....0..1
..1..2....2..1....2..2....2..2....2..1....0..2....1..0....1..2....0..1....0..1
..2..2....2..1....1..2....2..1....0..0....1..1....2..1....1..1....0..1....1..2
..1..2....1..2....2..2....1..0....2..1....1..2....1..2....0..0....1..1....2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 05 2014
STATUS
approved