OFFSET
1,2
COMMENTS
Column 2 of A198285.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 4*a(n-1) +a(n-2) -8*a(n-3).
Empirical g.f.: x*(1 - 3*x^2) / (1 - 4*x - x^2 + 8*x^3). - Colin Barker, May 14 2018
EXAMPLE
Some solutions for n=3:
..0..0..1..1....0..0..1..1....0..0..0..0....0..0..1..1....0..0..1..1
..0..0..1..1....0..0..1..1....0..1..1..0....0..0..1..1....0..0..1..1
..1..1..2..2....2..2..2..2....0..1..1..0....2..2..0..0....2..2..2..2
..1..1..2..2....2..0..0..2....0..0..0..0....2..2..0..0....2..1..1..2
..0..0..1..1....2..0..0..2....2..2..1..1....0..0..2..2....2..1..1..2
..0..0..1..1....2..2..2..2....2..2..1..1....0..0..2..2....2..2..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 23 2011
STATUS
approved