OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 2*a(n-3).
Conjectures from Colin Barker, Jul 18 2018: (Start)
G.f.: 2*x*(4 - 5*x - 3*x^2) / ((1 - 2*x)*(1 - 2*x - x^2)).
a(n) = -3*2^n + (3-2*sqrt(2))*(1-sqrt(2))^n + (1+sqrt(2))^n*(3+2*sqrt(2)).
(End)
EXAMPLE
Some solutions for n=5:
..1...-1....1...-1....0....1....1...-1...-1...-1...-1....1....0...-1....1....0
..1....0...-1....1...-1....0....0....0....0...-1...-1...-1...-1....0....1....1
..1...-1...-1....1....1...-1....1....1...-1....0...-1....0...-1....1...-1....1
..1....0...-1....0...-1....1....1...-1....1....1....1...-1....1...-1....0....1
..0...-1...-1...-1....1...-1...-1....0....1...-1....0...-1....0....1....1...-1
..1....1....0....1....1...-1....0...-1....0....0....1....0...-1...-1....0....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2012
STATUS
approved