OFFSET
1,1
COMMENTS
Column 3 of A207149.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) for n>10.
Empirical g.f.: x*(80 - 24*x - 59*x^2 + x^3 - x^4 + x^5 - x^6 + x^7 - x^8 + x^9) / ((1 - x)*(1 - 2*x^2)). - Colin Barker, Jun 19 2018
EXAMPLE
Some solutions for n=4:
..2..2..0..1....1..0..1..0....0..1..0..1....0..1..0..2....0..1..0..1
..1..0..2..0....0..1..0..1....2..0..1..0....2..0..1..0....1..0..1..0
..0..1..0..2....1..0..1..0....0..2..0..1....0..2..0..1....0..1..0..1
..1..0..1..0....0..1..0..1....2..0..2..0....1..0..2..0....1..0..1..0
..0..1..0..1....2..0..1..0....0..2..0..2....0..1..0..2....0..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 15 2012
STATUS
approved