OFFSET
1,1
COMMENTS
Column 2 of A209382.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 4*a(n-4) + 4*a(n-5).
Empirical g.f.: x*(8 + 9*x - 31*x^2 - 8*x^3 + 20*x^4) / ((1 - x)*(1 - 6*x^2 + 4*x^4)). - Colin Barker, Jul 09 2018
EXAMPLE
Some solutions for n=4:
..1..2..2....2..1..2....1..0..1....0..1..0....0..0..2....0..2..2....2..1..2
..0..0..1....2..0..2....2..0..2....2..2..0....2..1..2....0..1..0....2..0..0
..1..2..2....1..0..1....1..0..1....0..1..0....0..0..2....0..2..2....2..1..2
..0..0..1....2..2..2....2..0..2....0..2..2....2..1..2....0..1..0....0..0..2
..1..2..2....0..1..0....2..1..2....0..1..0....2..0..2....2..2..2....2..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 07 2012
STATUS
approved