OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-3) - 8*a(n-6) for n>13.
Empirical g.f.: x*(1929 + 1424*x + 724*x^2 - 10990*x^3 - 7920*x^4 - 3556*x^5 + 13108*x^6 + 9316*x^7 + 3536*x^8 + 1480*x^9 + 624*x^10 + 64*x^11 + 32*x^12) / ((1 - 2*x^3)*(1 - 4*x^3)). - Colin Barker, Dec 01 2018
EXAMPLE
Some solutions for n=4:
..3..3..1..3....0..2..1..0....0..1..1..0....3..1..2..0....1..3..3..1
..2..2..3..2....3..3..0..0....3..0..0..2....3..2..1..0....3..2..2..3
..2..2..3..2....0..1..2..3....0..1..1..0....0..3..0..3....3..2..2..3
..3..3..1..3....3..2..1..0....0..1..1..0....0..1..2..3....1..3..3..0
..2..2..3..1....0..0..3..3....2..0..0..3....3..3..0..0....3..2..2..3
..1..2..3..2....0..1..2..0....0..1..1..0....3..2..1..0....3..2..2..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 14 2014
STATUS
approved