OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..65
FORMULA
Empirical: a(n) = 4*a(n-1) + a(n-2) - 21*a(n-3) + 16*a(n-4) + 29*a(n-5) - 34*a(n-6) - 6*a(n-7) + 12*a(n-8).
Empirical g.f.: 2*x*(12 - 26*x - 61*x^2 + 145*x^3 + 75*x^4 - 228*x^5 - x^6 + 82*x^7) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 3*x^2)). - Colin Barker, Jul 19 2018
EXAMPLE
Some solutions for n=5:
.-2...-1...-1....1....2...-2...-2...-1....1....0....0....2....1....2...-2...-2
..2...-1...-1...-1...-1....0...-2....0...-1....1....1....2...-1....2....2...-2
..2...-1...-1....1...-1....2...-2...-1....1....0....0....2...-1....2...-2....2
..2...-1....2...-1....2....0...-2....0....1...-1....1...-2...-1...-2...-2...-2
.-2....1...-1....1...-1...-2....2...-1...-1....0....0....2...-1...-2....2...-2
..2....1....2....1....2....0....2...-2....1....1...-1...-2....1....2....2....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 16 2012
STATUS
approved