OFFSET
1,1
COMMENTS
Column 1 of A198485.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 55*a(n-1) -135*a(n-2) +81*a(n-3) for n>4.
Empirical g.f.: x*(5 - 82*x + 132*x^2 - 27*x^3) / ((1 - x)*(1 - 54*x + 81*x^2)). - Colin Barker, May 14 2018
EXAMPLE
Some solutions for n=3:
..0..1....0..0....0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1
..2..3....0..0....2..3....2..3....1..0....2..2....0..0....2..0....1..2....2..0
..1..1....1..2....0..2....1..2....2..1....2..2....1..2....1..2....3..0....0..3
..1..1....2..0....2..1....2..1....1..3....3..1....3..0....0..3....0..2....1..0
..3..2....0..3....1..2....1..0....0..1....2..0....2..2....1..0....1..3....0..1
..2..0....2..0....3..0....2..1....1..0....3..1....2..2....2..3....3..0....1..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 25 2011
STATUS
approved