OFFSET
1,1
COMMENTS
Column 3 of A180985.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) (=polynomial degree 7).
Conjectures from Colin Barker, Apr 12 2018: (Start)
G.f.: x*(4 - 18*x + 45*x^2 - 62*x^3 + 52*x^4 - 27*x^5 + 8*x^6 - x^7) / (1 - x)^8.
a(n) = (5040 + 7860*n + 4494*n^2 + 2044*n^3 + 525*n^4 + 175*n^5 + 21*n^6 + n^7) / 5040.
(End)
EXAMPLE
Some solutions for 5 X 3:
..0..0..0....0..0..0....0..0..0....0..0..1....0..1..1....0..0..0....0..0..0
..0..0..1....0..0..1....0..0..0....0..1..0....0..1..1....0..1..1....0..0..1
..1..1..0....1..1..1....0..0..0....0..1..0....1..0..1....0..1..1....0..1..1
..1..1..0....1..1..1....0..0..1....0..1..1....1..0..1....0..1..1....1..1..0
..1..1..0....1..1..1....1..1..1....1..0..1....1..1..1....0..1..1....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 09 2011
STATUS
approved