OFFSET
1,1
COMMENTS
Row 3 of A221573.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 1*n^3 - 1*n^2 + 3*n - 1.
Conjectures from Colin Barker, Aug 08 2018: (Start)
G.f.: x*(2 + x)*(1 + x^2) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>3.
(End)
EXAMPLE
Some solutions for n=6:
..1....0....5....2....5....0....6....6....6....0....6....0....1....1....6....5
..6....5....1....4....3....5....4....6....4....4....1....4....1....3....2....1
..4....5....1....4....1....2....0....4....2....0....6....4....3....0....5....5
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 20 2013
STATUS
approved