OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 4*a(n-2) - 2*a(n-3) + 4*a(n-4) - a(n-6) for n>7.
Empirical g.f.: 2*x*(5 + 14*x - 48*x^2 - 10*x^3 + 36*x^4 + 18*x^5 + 6*x^6) / ((1 - x)^2*(1 - x - x^2)^2). - Colin Barker, Feb 13 2019
EXAMPLE
Some solutions for n=4:
..0..1..0..1..0..1. .0..1..0..0..1..1. .0..0..1..1..0..0. .0..0..1..0..1..0
..0..0..1..0..1..0. .1..0..1..1..0..1. .0..1..0..0..1..1. .1..1..0..1..0..1
..0..1..0..1..0..1. .0..1..0..0..1..0. .1..0..1..1..0..0. .0..0..1..0..1..0
..1..0..1..0..1..0. .1..0..1..1..0..1. .0..1..0..0..1..1. .1..1..0..1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 03 2017
STATUS
approved