OFFSET
1,1
COMMENTS
Column 3 of A203378.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) -15*a(n-2) +6*a(n-3).
Empirical g.f.: 4*x*(27 - 56*x + 24*x^2) / (1 - 9*x + 15*x^2 - 6*x^3). - Colin Barker, Jun 04 2018
EXAMPLE
Some solutions for n=4:
..1..1..1..0....0..1..1..0....0..0..1..0....1..1..0..0....0..1..1..1
..0..1..1..1....1..1..0..1....0..0..0..1....0..1..1..0....0..0..1..1
..1..1..0..1....0..1..1..0....1..0..0..0....1..0..1..1....0..1..1..0
..1..0..1..1....1..1..1..1....0..1..0..1....0..0..0..1....1..0..1..1
..0..0..0..1....0..1..0..1....0..0..1..0....0..1..0..0....1..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 31 2011
STATUS
approved