OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 12*a(n-3) - 32*a(n-6) for n>8.
Empirical g.f.: x*(649 + 964*x + 1748*x^2 - 5284*x^3 - 4432*x^4 - 7792*x^5 + 9952*x^6 - 128*x^7) / ((1 - 2*x)*(1 + 2*x + 4*x^2)*(1 - 4*x^3)). - Colin Barker, Dec 04 2018
EXAMPLE
Some solutions for n=4:
..3..1..3..3..1..3....0..0..2..0..0..2....1..3..3..0..3..3....1..0..1..1..0..1
..2..2..3..2..2..3....0..1..1..0..1..1....2..3..2..2..3..2....0..0..3..0..0..2
..3..2..2..3..2..2....1..0..1..1..0..1....2..2..3..2..2..3....0..1..1..0..1..1
..3..1..3..3..1..3....0..0..3..0..0..3....1..3..3..0..3..3....1..0..1..1..0..1
..2..2..3..2..2..3....0..1..1..0..1..1....2..3..2..2..3..2....0..0..2..0..0..3
..3..2..2..3..2..2....1..0..1..1..0..1....2..2..3..2..2..3....0..1..1..0..1..1
..0..0..3..3..1..3....3..0..3..0..0..2....0..3..3..1..3..3....1..0..1..1..0..1
..2..2..3..2..2..3....0..1..1..0..1..2....2..3..2..2..3..2....3..0..3..0..0..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2014
STATUS
approved