OFFSET
1,1
COMMENTS
Column 1 of A251228.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - a(n-3).
Empirical g.f.: x*(14 + 7*x - 4*x^2) / (1 - 3*x - 2*x^2 + x^3). - Colin Barker, Feb 25 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0....1..0
..1..0....0..1....1..1....0..0....0..1....1..0....0..0....0..1....0..0....0..0
..1..0....0..0....0..0....0..1....1..1....1..0....0..0....0..1....1..0....0..1
..0..0....0..0....0..0....0..1....0..1....1..1....0..1....0..0....1..1....1..0
..1..0....0..0....1..0....1..1....0..0....0..0....1..1....0..0....1..0....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 30 2014
STATUS
approved