OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 11*a(n-1) - 30*a(n-2) - 21*a(n-3) + 112*a(n-4) + 63*a(n-5) - 119*a(n-6) - 120*a(n-7) - 30*a(n-8).
Empirical g.f.: x*(4 - 32*x + 29*x^2 + 152*x^3 - 31*x^4 - 285*x^5 - 215*x^6 - 49*x^7) / ((1 - x - x^2)*(1 - 2*x - 2*x^2)*(1 - 3*x - 3*x^2)*(1 - 5*x - 5*x^2)). - Colin Barker, Nov 01 2018
EXAMPLE
Some solutions for n=4:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..1....1....1....1....1....1....0....1....1....1....1....1....0....1....1....0
..0....2....2....0....0....1....1....0....0....1....2....2....1....2....1....1
..1....0....1....1....2....2....2....2....2....2....0....3....2....2....2....1
..0....2....2....0....1....1....1....0....3....0....3....0....2....1....1....0
..1....3....1....2....1....1....2....1....0....3....0....1....3....1....3....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 15 2014
STATUS
approved