OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 8*a(n-2) - 4*a(n-3) + a(n-4) + 14*a(n-5) - 8*a(n-6) for n>7.
Empirical g.f.: x*(1 + x)*(1 - 3*x - x^2 + 4*x^3 + 4*x^4 - 4*x^5) / ((1 - x)*(1 - 5*x + 3*x^2 + 7*x^3 + 6*x^4 - 8*x^5)). - Colin Barker, Oct 29 2018
EXAMPLE
Some solutions for n=4:
..0..1....0..1....0..1....0..1....0..0....0..0....0..1....0..1....0..0....0..0
..2..0....2..0....1..2....1..2....0..0....0..0....1..2....1..0....0..0....0..0
..1..2....0..2....2..1....0..1....0..0....0..0....2..0....0..1....1..1....1..2
..2..0....2..1....1..2....2..0....1..2....0..0....1..2....1..0....1..1....0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 15 2014
STATUS
approved