OFFSET
1,3
COMMENTS
Column 3 of A196017.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-4) -a(n-5) -2*a(n-6).
Empirical g.f.: x*(1 - x)*(1 + x + x^2 + 5*x^3 + 6*x^4) / (1 - x - x^2 - 3*x^4 + x^5 + 2*x^6). - Colin Barker, May 08 2018
EXAMPLE
All solutions for n=4:
..2..2..0....2..2..2....0..2..2....2..3..2....2..2..2....2..3..2....2..2..2
..3..3..2....2..0..2....2..3..3....3..4..3....2..0..2....3..3..3....2..0..2
..2..0..2....3..3..3....2..0..2....3..4..3....2..3..3....2..0..2....3..3..2
..2..2..2....2..3..2....2..2..2....2..3..2....0..2..2....2..2..2....2..2..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 26 2011
STATUS
approved