OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 2*a(n-2) + 3*a(n-3) +a(n-4).
Empirical g.f.: 6*x*(77 + 58*x + 68*x^2 + 21*x^3) / (1 - 3*x - 2*x^2 - 3*x^3 - x^4). - Colin Barker, Nov 06 2018
EXAMPLE
Some solutions for n=5:
..3....3....5....4....3....4....1....3....0....2....3....2....2....2....2....4
..5....0....4....4....3....2....1....4....1....4....4....2....5....1....2....5
..4....1....4....4....1....5....0....4....0....5....3....0....4....5....1....4
..4....0....3....5....0....5....2....4....2....5....3....4....2....1....1....5
..4....2....3....5....1....4....1....2....2....4....4....4....5....2....0....5
..4....2....3....5....0....5....1....5....2....4....5....2....4....5....3....2
..4....4....3....5....0....2....1....4....0....3....5....5....2....2....3....4
..3....2....0....5....1....4....3....5....0....3....2....5....2....4....4....4
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 27 2014
STATUS
approved