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) -2*a(n-3) +3*a(n-4) -a(n-5).
Empirical for n mod 2 = 0: a(n) = (13/6)*n^3 + (13/4)*n^2 + (10/3)*n + 1.
Empirical for n mod 2 = 1: a(n) = (13/6)*n^3 + (13/4)*n^2 + (10/3)*n + (5/4).
Empirical g.f.: x*(10 + 8*x + 5*x^2 + 4*x^3 - x^4) / ((1 - x)^4*(1 + x)). - Colin Barker, Nov 14 2018
EXAMPLE
Some solutions for n=6:
..0....4....3....5....0....2....4....0....5....0....4....1....2....4....5....1
..2....2....1....2....5....4....2....0....0....4....4....1....2....6....4....0
..0....2....1....4....2....4....5....1....3....1....4....2....5....2....6....3
..5....0....0....4....4....2....4....0....0....4....0....3....0....6....0....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 22 2014
STATUS
approved