OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 21*a(n-1) - 41*a(n-2) + 22*a(n-3) for n>4.
Empirical g.f.: x*(3 - 29*x + 65*x^2 - 44*x^3) / (1 - 21*x + 41*x^2 - 22*x^3). - Colin Barker, Oct 01 2018
EXAMPLE
Some solutions for n=5:
..0..0..1....0..0..1....0..0..1....0..0..2....0..0..2....0..0..0....0..0..0
..0..2..2....0..1..2....0..1..2....0..2..1....0..2..2....1..1..0....1..2..2
..0..2..2....0..2..0....0..2..1....0..1..1....2..0..1....0..2..2....0..2..2
..0..1..2....2..0..1....2..0..1....2..0..2....1..1..0....1..0..0....2..0..1
..0..0..1....1..2..2....2..2..2....2..2..0....1..0..0....1..0..0....0..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 14 2013
STATUS
approved