OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..57
FORMULA
Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 10*a(n-4) + 10*a(n-5) + 4*a(n-6) - 4*a(n-7).
Empirical g.f.: 2*x*(18 + 15*x - 89*x^2 - 53*x^3 + 117*x^4 + 26*x^5 - 42*x^6) / ((1 - x)*(1 - 2*x^2)*(1 - 4*x^2 + 2*x^4)). - Colin Barker, Jul 20 2018
EXAMPLE
Some solutions for n=5:
..2...-1...-3...-1....2....0....1...-2...-2...-2....0....3....1...-1....1....0
.-3....0...-2....0....0....2...-3...-1...-3....0...-2....0....0...-2....3...-1
..2....1...-1...-1...-2....0....1....0...-2...-2....0...-3...-2...-1....1....0
..0....2...-2....3....0...-1....3....1...-1....3....1....0....0....0...-3....2
..2....1...-1...-1....2....0....1....0....0...-2....0...-3...-2...-1....1....0
.-3....2...-2....0....0....2...-3...-1....1....0...-2....0....0...-2...-3...-1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 20 2012
STATUS
approved