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) - a(n-3) - 8*a(n-4) - 3*a(n-6) - 2*a(n-7) - 5*a(n-8) + a(n-9).
Empirical g.f.: x*(3 - 8*x^2 - 10*x^3 - 3*x^4 - 4*x^5 - 7*x^6 - 4*x^7 + x^8) / (1 - 3*x - x^2 + x^3 + 8*x^4 + 3*x^6 + 2*x^7 + 5*x^8 - x^9). - Colin Barker, Feb 23 2019
EXAMPLE
Some solutions for n=7:
..0..1. .1..0. .0..0. .1..0. .0..1. .1..0. .1..0. .1..1. .1..0. .1..1
..0..0. .0..1. .0..0. .0..1. .1..1. .0..0. .0..0. .1..0. .0..1. .1..0
..0..1. .0..0. .0..1. .1..1. .0..1. .0..0. .1..0. .1..1. .1..1. .0..0
..0..0. .0..0. .0..0. .0..0. .1..1. .0..1. .0..0. .1..0. .1..0. .0..1
..0..0. .0..0. .0..0. .1..0. .1..0. .0..0. .0..0. .0..0. .0..1. .0..0
..0..0. .0..0. .0..0. .0..0. .1..1. .0..1. .0..0. .0..0. .0..0. .1..0
..0..0. .1..0. .0..1. .0..1. .1..0. .1..1. .1..0. .1..0. .0..0. .0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 16 2017
STATUS
approved