OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..69
FORMULA
Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 9*a(n-3) + 10*a(n-4) + 2*a(n-5) - 4*a(n-6).
Empirical g.f.: 2*x*(4 - 7*x - 11*x^2 + 18*x^3 + 5*x^4 - 6*x^5) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)). - Colin Barker, Jul 18 2018
EXAMPLE
Some solutions for n=5:
..1...-1....1...-1...-1....1....0...-1...-1....0...-1....1....1...-1....0...-1
..1...-1....0....1...-1...-1....1...-1...-1....1....1....1....1...-1...-1...-1
.-1....0....1....1...-1...-1....1....1....0....0...-1....1....1...-1...-1....1
..1...-1....0....1....1...-1....0...-1...-1....1...-1...-1....1...-1...-1....1
..1....0....1....1....1....1....1...-1...-1....1....1....1....1...-1...-1...-1
.-1...-1....0....1...-1...-1....1...-1....0....1....1....1....0....0....0...-1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 14 2012
STATUS
approved