OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - 11*a(n-3) - 6*a(n-4) + 8*a(n-5) for n>6.
Empirical g.f.: x*(1 - x)*(1 - x - 6*x^2 - 2*x^3 + 4*x^4) / ((1 - 2*x)*(1 - 2*x - 6*x^2 - x^3 + 4*x^4)). - Colin Barker, Oct 29 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..1....0..1....0..1....0..1....0..1....0..0....0..0
..1..2....1..1....1..1....0..1....0..1....0..1....0..1....0..1....1..2....1..1
..1..2....0..2....0..0....1..2....2..1....2..0....2..2....0..1....1..2....2..2
..1..2....0..2....2..2....1..2....2..1....2..0....0..0....2..2....0..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 16 2014
STATUS
approved