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.: 2*x*(273 + 338*x + 557*x^2 - 2438*x^3 - 1846*x^4 - 3092*x^5 + 4408*x^6 - 136*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:
..1..2..0..1..1..0....0..2..0..0..2..0....2..3..2..2..3..2....1..3..3..0..0..3
..0..1..1..0..1..1....1..1..0..1..1..0....3..3..1..3..3..0....2..3..2..2..3..2
..0..2..0..0..2..0....0..1..1..0..1..1....3..2..2..3..2..2....2..2..3..2..2..3
..1..1..0..1..1..0....0..2..0..0..2..0....2..3..2..2..3..2....0..3..3..1..3..3
..0..1..1..0..1..1....1..1..0..1..1..0....3..3..1..3..3..1....2..3..2..2..3..2
..0..3..0..0..3..0....0..1..1..0..1..1....3..2..2..3..2..2....2..2..3..2..2..3
..1..1..0..1..1..0....0..2..0..0..2..0....2..3..2..2..3..2....1..3..3..1..3..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 18 2014
STATUS
approved