OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 5*a(n-1) - 3*a(n-2) for n>3.
Conjectures from Colin Barker, Sep 13 2018: (Start)
G.f.: 2*x*(1 - x + x^2) / (1 - 5*x + 3*x^2).
a(n) = -(2^(1-n)*((-11+sqrt(13))*(5+sqrt(13))^n + (5-sqrt(13))^n*(11+sqrt(13)))) / (9*sqrt(13)) for n>1.
(End)
EXAMPLE
Some solutions for n=4:
..1..0..0....1..0..0....1..0..0....1..0..1....1..0..1....1..0..1....1..0..1
..1..0..0....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1....1..0..0
..1..0..1....0..0..0....1..0..1....0..1..0....0..1..0....0..0..1....0..0..1
..0..0..1....1..0..0....0..0..1....0..1..0....0..0..0....0..0..0....1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 04 2013
STATUS
approved