OFFSET
1,1
COMMENTS
Column 4 of A209382.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 12*a(n-2) - 42*a(n-3) - 24*a(n-4) + 156*a(n-5) - 48*a(n-6) - 168*a(n-7) + 112*a(n-8).
Empirical g.f.: 4*x*(8 - 4*x - 117*x^2 + 107*x^3 + 449*x^4 - 472*x^5 - 502*x^6 + 548*x^7) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 12*x^2 + 28*x^4)). - Colin Barker, Jul 09 2018
EXAMPLE
Some solutions for n=4:
..0..2..2..2..0....2..0..2..0..2....1..2..2..2..1....0..0..2..1..2
..0..1..0..1..0....1..0..1..0..1....0..0..1..0..0....2..1..2..0..2
..2..2..2..2..2....2..2..2..0..2....1..2..2..2..1....2..0..2..1..2
..0..1..0..1..0....1..0..1..0..1....0..0..1..0..0....2..1..2..0..2
..0..2..0..2..2....2..0..2..2..2....1..2..2..2..1....0..0..2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 07 2012
STATUS
approved