OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 15*a(n-1) + 8*a(n-2) - 20*a(n-3).
Empirical g.f.: 2*x*(123 + 54*x - 160*x^2) / (1 - 15*x - 8*x^2 + 20*x^3). - Colin Barker, Nov 30 2018
EXAMPLE
Some solutions for n=3:
..1..3....3..1....2..2....3..1....1..1....0..3....0..1....0..3....2..1....3..1
..2..0....3..2....2..2....1..1....2..0....2..3....0..3....3..2....2..0....2..2
..3..1....3..0....0..2....1..3....0..0....1..2....2..2....0..1....1..3....2..0
..1..3....0..3....0..2....3..2....2..0....1..1....3..2....2..1....3..3....3..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 03 2014
STATUS
approved