OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/720)*n^6 + (1/48)*n^5 + (29/144)*n^4 + (5/16)*n^3 + (647/360)*n^2 + (2/3)*n + 1.
Conjectures from Colin Barker, Sep 09 2018: (Start)
G.f.: x*(4 - 12*x + 22*x^2 - 23*x^3 + 14*x^4 - 5*x^5 + x^6) / (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=4.
..1..0....1..0....0..0....0..0....1..0....0..1....0..1....0..0....0..0....0..1
..1..0....0..0....0..1....0..1....0..1....1..1....1..1....0..0....1..0....1..1
..0..0....0..1....1..0....1..1....0..0....1..1....1..0....0..1....0..0....0..0
..0..0....0..1....1..0....1..1....0..0....0..1....0..0....1..1....0..1....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 19 2013
STATUS
approved