OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = a(n-1) + 6*a(n-3) - 6*a(n-4) - 4*a(n-6) + 4*a(n-7).
Empirical g.f.: 2*x*(21 + 14*x + 24*x^2 - 86*x^3 - 12*x^4 - 20*x^5 + 56*x^6) / ((1 - x)*(1 - 6*x^3 + 4*x^6)). - Colin Barker, Nov 08 2018
EXAMPLE
Some solutions for n=6:
..2....0....4....1....1....5....3....5....1....0....5....2....5....4....5....2
..0....1....0....3....2....1....1....3....5....2....4....1....1....0....1....4
..1....2....2....2....3....3....2....4....3....1....3....3....3....2....3....0
..2....3....4....4....1....2....3....5....4....3....2....5....5....1....2....2
..0....4....0....3....2....1....4....3....5....2....1....1....1....3....4....1
..4....2....2....5....3....3....5....1....3....4....0....3....3....5....3....3
..2....3....1....1....1....2....3....2....4....3....2....5....5....4....2....2
..3....1....0....3....2....4....4....0....2....2....4....1....4....3....4....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 06 2014
STATUS
approved