OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..64
FORMULA
Empirical: a(n) = a(n-1) + 5*a(n-2) - 5*a(n-3) - 6*a(n-4) + 6*a(n-5).
Empirical g.f.: 2*x*(8 + 6*x - 32*x^2 - 15*x^3 + 29*x^4) / ((1 - x)*(1 - 2*x^2)*(1 - 3*x^2)). - Colin Barker, Jul 19 2018
EXAMPLE
Some solutions for n=5:
.-2....0....0....1....0....2....1....0....1...-1...-1....0....1....0....1...-1
.-1....2...-2....0...-1....1....0....1....0....0...-2...-1....0....2....2....0
..0....0....0....1...-2....0....1....0....1....1...-1....0...-1....0....1...-1
..1...-2...-2....2...-1...-1....2....1....0....0....0....1....0....2....0....0
..2....0....0....1...-2...-2....1....0...-1...-1....1....2...-1....0...-1....1
..1...-2...-2....0...-1...-1....2...-2...-2...-2....2....1...-2...-1....0....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 16 2012
STATUS
approved