OFFSET
1,1
COMMENTS
Column 3 of A219291.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/4)*n^3 - (1/24)*n^2 + (27/4)*n - 11 for n>2.
Conjectures from Colin Barker, Jul 25 2018: (Start)
G.f.: x*(3 - 9*x + 19*x^2 - 23*x^3 + 14*x^4 - 2*x^5 - x^6) / (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>7.
(End)
EXAMPLE
Some solutions for n=3:
..0..0..1....0..0..1....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..1....0..0..1....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1
..0..1..1....0..0..0....1..0..0....0..1..0....1..1..1....0..0..1....0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 17 2012
STATUS
approved