OFFSET
1,1
COMMENTS
Column 1 of A203923.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) +6*a(n-3) +4*a(n-4).
Empirical g.f.: 8*x*(14 + 7*x + 28*x^2 + 16*x^3) / ((1 + 2*x^2)*(1 - 3*x - 2*x^2)). - Colin Barker, Jun 05 2018
EXAMPLE
Some solutions for n=3:
..0..0..0....0..1..1....0..0..1....0..0..0....0..1..0....0..1..0....0..0..1
..1..0..0....1..0..1....1..0..1....1..0..0....0..0..0....0..0..0....1..1..1
..0..1..1....0..1..0....0..1..0....1..1..0....0..0..0....1..0..0....1..1..1
..1..1..1....1..0..0....1..0..1....0..1..1....0..0..1....0..1..0....1..1..1
..1..1..1....0..0..1....1..0..0....1..0..1....0..0..0....0..0..1....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 07 2012
STATUS
approved