OFFSET
1,1
COMMENTS
Column 2 of A206700.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) -3*a(n-2) -25*a(n-3) +9*a(n-4) +3*a(n-5) -a(n-6).
Empirical g.f.: x*(9 - 26*x^2 + 9*x^3 + 3*x^4 - x^5) / ((1 - 9*x + 6*x^2 - x^3)*(1 - 3*x^2 - x^3)). - Colin Barker, Feb 23 2018
EXAMPLE
Some solutions for n=4:
..0..1....0..2....0..2....2..0....0..2....2..1....0..1....1..1....1..2....1..2
..2..1....2..2....1..1....0..2....0..2....0..2....2..1....1..0....2..2....2..0
..2..2....0..0....0..0....1..0....2..2....1..2....2..0....1..2....1..2....0..1
..0..0....2..1....0..1....1..2....0..2....0..1....0..1....1..2....2..2....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 11 2012
STATUS
approved