OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 5*a(n-2) - 5*a(n-4) + 2*a(n-6).
Empirical g.f.: x*(1 + 3*x - x^2 - 4*x^3 + 2*x^5) / (1 - 5*x^2 + 5*x^4 - 2*x^6). - Colin Barker, Sep 26 2018
EXAMPLE
Some solutions for n=4:
..x..0..x....x..0..x....x..0..x....x..0..x....x..0..x....x..0..x....x..0..x
..1..x..1....0..x..1....1..x..1....1..x..0....1..x..0....1..x..1....1..x..1
..x..1..x....x..1..x....x..0..x....x..1..x....x..1..x....x..0..x....x..0..x
..0..x..0....0..x..1....1..x..0....1..x..0....0..x..1....0..x..0....0..x..1
..x..1..x....x..0..x....x..1..x....x..0..x....x..0..x....x..1..x....x..1..x
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 03 2013
STATUS
approved