OFFSET
1,2
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>10.
Empirical g.f.: 2*x^2*(19 + 8*x - 125*x^2 + 69*x^3 + 94*x^4 - 55*x^5 - 17*x^6 + 13*x^7 + x^8) / ((1 - x)^2*(1 - x - x^2)^2). - Colin Barker, Feb 18 2019
EXAMPLE
Some solutions for n=4:
..0..0..0..1. .0..0..0..1. .0..0..1..0. .0..1..1..0. .0..0..1..0
..0..1..0..0. .1..1..0..0. .1..0..1..1. .0..0..1..1. .0..1..0..1
..0..1..1..0. .0..1..1..0. .1..0..0..1. .1..0..0..1. .0..1..0..1
..0..0..1..1. .0..0..1..0. .1..0..1..0. .1..0..1..0. .0..1..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 17 2017
STATUS
approved