OFFSET
1,2
COMMENTS
Column 5 of A221683.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) +3*a(n-2) -6*a(n-3) +19*a(n-4) +5*a(n-5) +a(n-6).
Empirical g.f.: x^2*(2 - 3*x + 6*x^2 + 2*x^3) / (1 - 4*x - 3*x^2 + 6*x^3 - 19*x^4 - 5*x^5 - x^6). - Colin Barker, Oct 19 2017
EXAMPLE
Some solutions for n=6
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..0....0....0....0....0....0....1....0....0....0....1....0....1....1....0....0
..5....1....4....3....3....1....2....4....1....1....2....1....1....1....0....4
..4....3....4....3....2....2....3....5....1....2....3....1....2....1....0....4
..5....3....2....0....1....3....2....2....1....0....5....1....3....1....1....3
..5....3....2....1....1....4....1....2....0....1....4....1....2....1....0....4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 22 2013
STATUS
approved