OFFSET
1,2
COMMENTS
Column 2 of A222165.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) - 3*a(n-3) - 2*a(n-4) - 2*a(n-5) - a(n-6).
Empirical g.f.: x*(1 + x)^2 / ((1 - x - x^2)*(1 - 2*x - 2*x^2 - x^3 - x^4)). - Colin Barker, Aug 15 2018
EXAMPLE
Some solutions for n=3:
..0....0....0....1....1....0....1....0....0....0....0....1....1....1....0....1
..1....2....2....1....1....1....0....2....1....0....0....1....1....2....1....2
..3....1....2....3....1....1....2....1....2....3....2....1....2....1....2....2
..1....1....1....0....1....2....1....2....2....1....2....2....0....1....1....0
..0....1....0....0....1....1....1....0....0....1....1....0....1....0....1....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 10 2013
STATUS
approved