OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) + 8*a(n-2) - 24*a(n-3) - 38*a(n-4) + 4*a(n-5) + 12*a(n-6) - a(n-8).
Empirical g.f.: x*(7 + 4*x - 41*x^2 - 37*x^3 + 13*x^4 + 6*x^5 + x^6 - x^7) / (1 - 2*x - 6*x^2 + x^4)^2. - Colin Barker, Jan 14 2019
EXAMPLE
Some solutions for n=4:
..1..0..1. .0..0..1. .0..0..0. .1..0..1. .0..0..0. .0..0..1. .0..1..0
..1..0..0. .1..0..0. .0..0..1. .0..0..0. .0..1..0. .1..1..0. .0..0..0
..0..0..0. .0..0..0. .1..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0
..0..0..1. .1..1..0. .0..1..1. .0..1..0. .1..1..0. .0..0..1. .0..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 12 2016
STATUS
approved