OFFSET
1,1
COMMENTS
Column 3 of A280604.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 3*a(n-3) + 2*a(n-4) + 3*a(n-5) - 2*a(n-6) for n>8.
Empirical g.f.: x*(4 + 2*x - 15*x^2 + 2*x^3 + 10*x^4 - 2*x^5 - 5*x^6 + 3*x^7) / ((1 - x)^3*(1 - x - 3*x^2 - 2*x^3)). - Colin Barker, Mar 22 2018
EXAMPLE
Some solutions for n=4:
..0..1..0. .0..0..0. .0..0..1. .0..0..0. .0..1..1. .0..1..0. .0..1..0
..1..0..1. .1..1..1. .1..1..0. .1..1..0. .1..0..1. .0..1..0. .1..0..0
..1..0..1. .0..0..1. .0..0..1. .1..0..1. .0..1..0. .1..0..1. .1..1..1
..0..1..0. .1..0..0. .1..1..0. .0..1..0. .0..1..1. .0..1..0. .0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2017
STATUS
approved