OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..63
FORMULA
Empirical: a(n) = 5*a(n-1) - 4*a(n-2) - 16*a(n-3) + 27*a(n-4) + 8*a(n-5) - 35*a(n-6) + 10*a(n-7) + 10*a(n-8) - 4*a(n-9).
Empirical g.f.: 2*x*(4 - 11*x - 8*x^2 + 40*x^3 - 9*x^4 - 42*x^5 + 23*x^6 + 10*x^7 - 6*x^8) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - x - 2*x^2 + x^3)). - Colin Barker, Jul 18 2018
EXAMPLE
Some solutions for n=5:
.-1....1....1....1...-1...-1....0...-1....0...-1...-1....1...-1...-1....1...-1
..1....1....0...-1....0....1....1....1....1...-1...-1...-1....1....0....1....0
.-1...-1....1....0...-1....1...-1....1....0...-1....1....1...-1...-1....1....1
..1....1....0....1....1...-1....1...-1....1....1...-1...-1...-1....0....1...-1
.-1...-1...-1...-1....0....0...-1....1....0....1....1....0...-1....1...-1....1
.-1....1....1....1...-1...-1....0....1....1...-1....1....1....1...-1....0...-1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 14 2012
STATUS
approved