OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..145
FORMULA
Empirical: a(n) = 2*a(n-1) -2*a(n-3) +a(n-4).
Empirical for n mod 2 = 0: a(n) = (9/2)*n^2 + 4*n + 1.
Empirical for n mod 2 = 1: a(n) = (9/2)*n^2 + 4*n - (1/2).
Empirical g.f.: x*(8 + 11*x - 2*x^2 + x^3) / ((1 - x)^3*(1 + x)). - Colin Barker, Nov 12 2018
EXAMPLE
Some solutions for n=6:
..2....1....5....0....0....4....1....6....5....1....2....1....4....5....2....3
..2....4....5....4....6....4....3....3....5....4....5....3....4....5....2....2
..4....1....0....0....6....3....3....0....4....4....2....3....2....6....6....1
..6....1....5....0....0....4....1....0....3....1....2....5....0....5....2....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 14 2014
STATUS
approved