OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-3) for n>5.
Empirical g.f.: x*(25 + 37*x + 51*x^2 - 12*x^3 - 6*x^4) / (1 - 3*x^3). - Colin Barker, Dec 08 2018
EXAMPLE
Some solutions for n=4:
..0..1..2....0..0..0....0..1..2....0..1..2....0..0..0....0..1..2....0..1..2
..2..1..0....1..0..2....0..0..0....3..1..0....1..2..0....2..2..2....3..0..2
..1..1..1....2..0..3....0..2..1....1..1..1....2..1..0....1..3..2....2..2..2
..0..1..2....0..0..0....0..1..2....0..1..3....0..0..0....3..1..2....1..3..2
..2..1..0....3..0..2....0..0..0....2..1..0....1..2..0....2..2..2....3..1..2
..1..1..1....2..0..3....0..2..1....1..1..1....2..3..0....1..0..2....2..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 26 2014
STATUS
approved