OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (2/15)*n^5 + (7/6)*n^4 + (25/6)*n^3 + (19/3)*n^2 + (21/5)*n + 1.
Conjectures from Colin Barker, Sep 11 2018: (Start)
G.f.: x*(17 - 11*x + 19*x^2 - 14*x^3 + 6*x^4 - x^5) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.
(End)
EXAMPLE
Some solutions for n=4:
..2....2....0....2....3....4....4....3....3....4....4....4....4....2....4....1
..0....1....0....1....3....4....4....1....1....2....2....3....2....1....0....4
..2....1....1....0....2....3....3....2....1....0....2....1....1....2....1....4
..3....0....3....2....2....2....2....2....1....2....1....3....2....2....1....4
..3....0....3....4....1....2....1....4....0....3....2....4....4....2....2....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 22 2013
STATUS
approved