OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 10*a(n-3) + 5*a(n-4) - 14*a(n-5) + 9*a(n-6) - 2*a(n-7) for n>8.
Empirical g.f.: x*(192 - 536*x - 35*x^2 + 1460*x^3 - 1768*x^4 + 674*x^5 + 85*x^6 - 82*x^7) / ((1 - x)^5*(1 + x)*(1 - 2*x)). - Colin Barker, Nov 24 2018
EXAMPLE
Some solutions for n=4:
..0..0..1..1....0..0..0..2....1..1..2..2....0..0..0..2....1..0..0..2
..0..0..0..0....1..0..0..1....0..0..0..0....0..0..0..2....1..0..0..2
..0..0..0..0....2..0..0..1....1..1..1..1....1..0..0..0....1..0..0..2
..0..0..0..0....2..0..0..1....0..0..0..0....1..0..0..0....1..0..0..2
..1..1..1..1....2..0..0..1....2..2..1..1....2..1..1..1....2..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 29 2014
STATUS
approved