OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = (1/5040)*n^7 + (1/240)*n^6 + (31/720)*n^5 + (1/16)*n^4 + (41/360)*n^3 + (13/30)*n^2 + (12/35)*n.
Conjectures from Colin Barker, Feb 09 2019: (Start)
G.f.: x*(1 - 2*x + 7*x^2 - 8*x^3 + 3*x^4) / (1 - x)^8.
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) for n>8.
(End)
EXAMPLE
Some solutions for n=4:
..1..1. .0..0. .0..0. .0..0. .0..1. .1..1. .1..1. .1..1. .1..1. .0..1
..1..1. .1..1. .1..0. .1..0. .1..1. .1..1. .0..0. .0..1. .0..0. .1..1
..1..1. .0..1. .1..0. .1..0. .0..1. .0..0. .0..0. .1..0. .0..1. .1..0
..0..1. .0..1. .1..0. .1..1. .1..0. .0..0. .0..0. .1..0. .1..1. .1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 19 2016
STATUS
approved