OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - a(n-5) - a(n-6) for n>8.
Empirical g.f.: 2*x*(406 + 315*x + 590*x^2 - 1568*x^3 - 1519*x^4 - 1188*x^5 - 519*x^6 + 147*x^7) / ((1 - x + 2*x^2 - x^3)*(1 - 2*x - 3*x^2 - x^3)). - Colin Barker, Dec 02 2018
EXAMPLE
Some solutions for n=4:
..2..0..2..0..1....2..0..2..1..1....1..0..2..0..1....1..2..1..1..1
..0..2..0..2..0....0..2..0..2..0....1..2..0..2..1....1..0..2..0..1
..2..0..2..0..1....2..0..2..0..1....2..0..2..0..1....0..2..0..2..0
..0..2..0..2..1....0..2..0..2..1....0..2..0..2..0....1..0..2..0..2
..2..0..2..0..1....2..0..2..0..2....2..0..2..0..2....1..2..0..2..1
..1..2..0..1..1....1..2..0..1..1....1..1..1..2..1....2..0..2..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 15 2014
STATUS
approved