OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) - 4*a(n-3) + a(n-4) + 2*a(n-5) - a(n-6).
Empirical for n mod 2 = 0: a(n) = (29/12)*n^3 + (11/4)*n^2 + (17/6)*n + 1.
Empirical for n mod 2 = 1: a(n) = (29/12)*n^3 + (11/4)*n^2 + (19/12)*n + (5/4).
Empirical g.f.: x*(8 + 21*x + 14*x^2 + 14*x^3 + 2*x^4 - x^5) / ((1 - x)^4*(1 + x)^2). - Colin Barker, Nov 12 2018
EXAMPLE
Some solutions for n=6:
..4....0....3....6....1....1....6....2....0....5....0....1....4....0....4....0
..5....2....3....1....4....2....5....2....3....5....1....3....1....3....0....3
..5....5....4....1....5....3....0....4....5....3....6....0....5....1....5....4
..6....6....3....6....3....5....6....6....0....5....2....1....6....0....4....6
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 13 2014
STATUS
approved