OFFSET
1,2
COMMENTS
Row 7 of A221515.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 1*n^6 + 1*n^5 - 29*n^4 + 104*n^3 - 173*n^2 + 136*n - 40 for n>3.
Conjectures from Colin Barker, Aug 06 2018: (Start)
G.f.: 2*x^2*(4 + 96*x + 260*x^2 + 126*x^3 - 136*x^4 + 43*x^5 - 49*x^6 + 19*x^7 - 3*x^8) / (1 - x)^7.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>10.
(End)
EXAMPLE
Some solutions for n=6:
..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
..6....5....3....5....5....4....3....5....6....6....3....6....6....6....3....5
..0....1....0....1....0....6....5....5....2....5....6....1....2....0....0....6
..5....1....2....4....2....6....2....1....4....2....6....0....1....2....5....0
..2....5....4....0....4....0....6....5....2....6....0....6....5....5....1....0
..6....6....5....2....5....0....2....2....4....3....3....5....5....0....6....4
..0....4....2....6....0....2....4....0....1....5....1....3....2....5....3....6
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 18 2013
STATUS
approved