OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-2) + 2*a(n-3) + 8*a(n-4).
Empirical g.f.: 4*x*(4 + 8*x + 11*x^2 + 14*x^3) / ((1 - 2*x)*(1 + 2*x + 3*x^2 + 4*x^3)). - Colin Barker, Oct 21 2018
EXAMPLE
Some solutions for n=5:
..1..1....1..1....1..0....1..1....1..1....0..0....1..1....0..0....0..0....1..1
..0..1....0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1....1..1
..0..1....0..0....0..0....1..0....1..0....1..1....0..1....0..1....0..1....0..0
..0..0....1..1....1..1....1..1....0..0....1..0....1..1....1..1....1..1....1..0
..1..1....1..0....0..1....0..0....1..1....1..0....0..0....0..0....0..0....1..0
..1..0....0..1....0..1....1..0....1..1....0..0....1..0....0..0....1..0....1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 22 2014
STATUS
approved