OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) + 21*a(n-2) - 14*a(n-3).
Empirical g.f.: 84*x*(1 - 2*x) / (1 - 9*x - 21*x^2 + 14*x^3). - Colin Barker, Oct 24 2018
EXAMPLE
Some solutions for n=4:
..3..1....1..2....2..1....3..2....3..1....2..0....2..3....2..3....3..0....0..3
..2..3....0..1....0..3....1..0....1..3....3..2....3..2....1..0....1..3....2..0
..0..3....0..3....2..3....3..1....3..0....0..3....1..2....2..0....2..1....1..3
..0..2....1..0....1..2....1..3....1..0....3..2....0..1....1..2....3..0....2..0
..1..0....0..1....3..0....2..0....3..2....2..3....2..3....3..1....0..3....1..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 28 2014
STATUS
approved
