OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 7*a(n-2) - 3*a(n-3) + 3*a(n-4) - 7*a(n-5) + 2*a(n-6) - 2*a(n-7) + 2*a(n-8).
Empirical g.f.: 2*x*(1 + x + x^2)*(2 + 3*x - 3*x^2 - x^3 - 2*x^4 + 2*x^5) / (1 - x - 7*x^2 + 3*x^3 - 3*x^4 + 7*x^5 - 2*x^6 + 2*x^7 - 2*x^8). - Colin Barker, Oct 03 2018
EXAMPLE
Some solutions for n=7:
..2..0..2....0..1..0....0..1..2....2..1..0....1..2..1....1..2..1....1..2..1
..0..1..0....1..2..1....2..0..1....1..0..1....0..1..0....2..1..0....0..1..0
..1..2..1....2..1..2....0..2..0....2..1..2....1..2..1....1..0..1....1..0..1
..2..1..0....1..2..1....1..0..1....1..0..1....2..1..2....0..1..2....2..1..2
..0..2..1....0..1..2....2..1..2....0..1..2....1..2..1....2..0..1....1..0..1
..1..0..2....1..2..1....1..0..1....1..2..1....0..1..2....1..2..0....0..1..0
..2..1..0....0..1..0....2..1..2....2..1..2....1..2..1....2..1..2....1..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 17 2013
STATUS
approved