OFFSET
1,1
COMMENTS
Column 3 of A209511.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) - 15*a(n-2) + 6*a(n-3).
Empirical g.f.: 3*x*(27 - 56*x + 24*x^2) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Jul 10 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..2....2..0..1..2....1..2..0..1....2..1..2..1....0..1..2..1
..1..0..1..0....1..2..0..1....2..0..1..0....1..2..0..2....2..0..1..2
..2..1..0..1....2..1..2..0....1..2..0..1....2..0..2..1....0..1..2..1
..0..2..1..2....0..2..1..2....2..1..2..0....1..2..0..2....2..0..1..2
..1..0..2..1....1..0..2..1....0..2..0..2....2..0..1..0....0..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 09 2012
STATUS
approved