OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 5*a(n-1) + 9*a(n-2) - 57*a(n-3) - 36*a(n-4) + 196*a(n-5) + 96*a(n-6) - 124*a(n-7) + 24*a(n-8).
Empirical g.f.: 4*x*(5 - 5*x - 69*x^2 + 11*x^3 + 264*x^4 + 92*x^5 - 150*x^6 + 30*x^7) / ((1 - 2*x - 6*x^2)*(1 - x - 6*x^2 + 2*x^3)*(1 - 2*x - 5*x^2 + 2*x^3)). - Colin Barker, Jul 17 2018
EXAMPLE
Some solutions for n=5:
.-1...-2....1....2...-2....2...-1...-2....1....1...-2...-2...-1....2....1...-2
..2....1...-1....0....1...-2....1....2...-2...-2....1....2....2....0....0....0
..0....0...-2...-1....2....1...-1....1....0...-1....2....1....1...-1....1...-1
..2....1....1....2....0...-2....1...-1....2...-2...-2...-1....0....0...-2....0
.-1...-2...-1....0....1....2....0....2...-2....0....1....0...-1....1....0....2
..0....2....0....1....0....0....1...-2....0...-1....0....1....0....2....2...-1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2012
STATUS
approved