OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..72
FORMULA
Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 24*a(n-3) + 4*a(n-4) + 36*a(n-5) - 24*a(n-6).
Empirical g.f.: 4*x*(4 - x - 30*x^2 + 14*x^3 + 42*x^4 - 24*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 6*x^2)). - Colin Barker, Jul 19 2018
EXAMPLE
Some solutions for n=5:
..0....0....1...-1....0....1...-1....2....0....1...-1....1....2...-1...-2....0
..1....1....2....2....1....2...-2....1....1....2...-2...-2....1....2...-1...-1
..2....2...-1....1....2....0....1....2...-2....0....1....1...-2...-1....2....2
.-1....0...-2....2....1....2....0....1...-1....1....2....0....1...-2...-1....1
..2....2....1....1...-2....0....1...-2...-2....0....1...-1....2....1...-2...-2
..1....0....0....0...-1....1....2...-1....1....1...-2....0....1....0....1....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 16 2012
STATUS
approved