OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/60)*n^5 - (1/12)*n^4 + (5/12)*n^3 + (1/12)*n^2 - (13/30)*n + 1 for n>1.
Conjectures from Colin Barker, Sep 07 2018: (Start)
G.f.: x*(2 - 9*x + 21*x^2 - 26*x^3 + 20*x^4 - 7*x^5 + x^6) / (1 - x)^6.
a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>7.
(End)
EXAMPLE
Some solutions for n=4:
..1..1....1..1....1..1....1..0....1..0....1..1....1..1....1..1....1..1....1..1
..1..0....1..1....1..0....0..1....0..1....1..1....1..0....1..0....1..1....1..0
..0..1....1..1....1..0....0..1....1..1....1..0....0..1....1..1....1..0....1..0
..0..0....1..0....0..1....1..0....1..1....1..1....1..0....1..1....0..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 04 2013
STATUS
approved