OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/3)*n^4 + (8/3)*n^3 + (14/3)*n^2 + (10/3)*n + 1.
Conjectures from Colin Barker, Dec 09 2018: (Start)
G.f.: x*(3 - x)*(4 - x + 2*x^2 - x^3) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
(End)
EXAMPLE
Some solutions for n=10:
..7....4....7....9....1....4....7....6....5....4....4....4....6....9....9....1
..2....6...10....0....2....1...10....7....9....6...10....0....6....2....5....6
..0....9....9....1....9....0....9...10....8....8....6....3....7....1....9....3
..4....0....4....3....2....1....5....3....1....6....6....7....2....4....9....2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 27 2014
STATUS
approved