OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) + 3*a(n-3) - 2*a(n-4) + a(n-5) - 2*a(n-6) + a(n-7) - a(n-8).
Empirical g.f.: x*(4 + 3*x + x^2 - x^3 - x^4 - x^5 - x^7) / (1 - 3*x - x^2 - 3*x^3 + 2*x^4 - x^5 + 2*x^6 - x^7 + x^8). - Colin Barker, Feb 21 2019
EXAMPLE
Some solutions for n=4:
..1..0. .1..1. .1..1. .0..1. .1..0. .0..1. .1..1. .0..1. .1..1. .1..1
..1..1. .1..0. .0..1. .0..1. .0..1. .1..0. .0..1. .1..1. .0..1. .0..0
..0..0. .0..1. .0..0. .1..0. .0..1. .0..1. .0..1. .0..0. .1..0. .0..1
..0..0. .0..1. .1..1. .0..0. .0..1. .0..0. .0..0. .1..1. .1..0. .0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 04 2017
STATUS
approved