OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 14*a(n-1) - 85*a(n-2) + 294*a(n-3) - 639*a(n-4) + 906*a(n-5) - 839*a(n-6) + 490*a(n-7) - 164*a(n-8) + 24*a(n-9).
Empirical g.f.: x*(222 - 1928*x + 7379*x^2 - 16515*x^3 + 23687*x^4 - 22151*x^5 + 13066*x^6 - 4404*x^7 + 648*x^8) / ((1 - x)^5*(1 - 2*x)^3*(1 - 3*x)). - Colin Barker, Nov 14 2018
EXAMPLE
Some solutions for n=5:
..2..2..0....2..2..1....1..1..0....2..0..0....2..1..1....2..1..0....2..0..0
..1..2..0....1..1..0....2..2..2....2..0..0....1..0..0....2..2..1....2..1..1
..1..2..0....2..2..1....1..1..1....2..0..1....2..1..1....1..1..0....1..0..0
..1..2..0....0..0..1....1..1..1....2..1..2....2..1..1....0..1..0....0..0..0
..1..2..0....1..1..2....0..0..0....1..0..2....1..0..0....0..1..0....0..0..0
..0..1..2....0..0..1....1..1..1....0..0..2....1..0..2....0..1..2....1..2..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 24 2014
STATUS
approved