OFFSET
1,1
COMMENTS
Column 4 of A208709.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 13*a(n-1) - 4*a(n-2).
Conjectures from Colin Barker, Jul 06 2018: (Start)
G.f.: 4*x*(2 - x) / (1 - 13*x + 4*x^2).
a(n) = (2^(-1-n)*((13-3*sqrt(17))^n*(-1+sqrt(17)) + (1+sqrt(17))*(13+3*sqrt(17))^n)) / sqrt(17).
(End)
EXAMPLE
Some solutions for n=4:
..0..1..1..1....0..0..0..0....0..1..0..1....0..1..1..1....0..1..1..0
..0..0..1..1....0..1..1..0....0..0..1..0....1..0..0..0....0..0..1..0
..1..0..0..1....1..0..1..1....0..1..1..1....0..1..1..1....0..0..1..1
..0..1..1..1....1..1..0..1....1..0..1..1....1..0..0..0....1..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 01 2012
STATUS
approved