OFFSET
1,2
COMMENTS
Column 2 of A198604.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 9*a(n-1) -4*a(n-2) -36*a(n-3) +5*a(n-4) +27*a(n-5).
Empirical g.f.: x*(1 - 4*x - 9*x^2 + 19*x^3 + 29*x^4) / ((1 - x)*(1 + x)*(1 - 9*x + 5*x^2 + 27*x^3)). - Colin Barker, May 14 2018
EXAMPLE
Some solutions for n=3:
..0..0..1..1....0..0..0..0....0..0..0..0....0..0..1..1....0..0..1..1
..0..0..1..1....0..1..1..0....0..1..1..0....0..0..1..1....0..0..1..1
..1..1..0..0....0..1..1..0....0..1..1..0....2..2..2..2....2..2..3..3
..1..1..0..0....0..0..0..0....0..0..0..0....2..0..0..2....2..2..3..3
..0..0..1..1....1..1..2..2....2..2..1..1....2..0..0..2....3..3..2..2
..0..0..1..1....1..1..2..2....2..2..1..1....2..2..2..2....3..3..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 27 2011
STATUS
approved