OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 20*a(n-3) + 6*a(n-4) + 12*a(n-5).
Empirical g.f.: x*(44 - 47*x - 170*x^2 + 66*x^3 + 108*x^4) / ((1 - x)*(1 - 2*x - 2*x^2)*(1 - 3*x - 6*x^2)). - Colin Barker, Nov 14 2018
EXAMPLE
Some solutions for n=6:
..0..2....1..0....0..1....0..2....1..0....0..1....2..0....1..0....0..2....0..1
..0..1....0..0....0..2....0..2....0..0....0..2....0..0....0..2....0..0....0..1
..2..0....0..2....0..0....0..2....2..0....0..2....1..0....0..1....0..0....1..0
..0..2....1..0....1..0....0..1....0..0....0..1....0..2....0..0....0..1....0..0
..2..0....0..2....0..2....0..1....1..2....1..0....0..1....0..1....0..0....0..1
..0..1....0..2....1..1....0..1....2..1....0..0....0..1....0..2....0..1....0..2
..0..0....1..0....2..1....0..1....1..2....1..0....2..2....0..2....0..2....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 23 2014
STATUS
approved