OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = n^6 + 3*n^5 + 5*n^4 + 5*n^3 + 4*n^2 + 2*n.
Conjectures from Colin Barker, Nov 10 2018: (Start)
G.f.: 20*x*(1 + 4*x + x^2)^2 / (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>7.
(End)
EXAMPLE
Some solutions for n=6:
..1....1....2....5....6....4....6....3....4....4....1....3....5....4....0....2
..5....3....0....1....3....2....0....4....3....5....3....1....5....2....6....4
..1....0....1....1....2....6....5....6....6....4....3....3....3....2....5....2
..1....3....2....4....0....2....5....4....6....2....1....2....6....3....1....4
..5....5....3....6....6....3....6....1....2....1....6....6....2....2....0....4
..5....1....0....3....1....0....6....0....5....2....1....0....1....4....5....1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 10 2014
STATUS
approved