OFFSET
1,3
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 8*a(n-1) - 20*a(n-2) + 32*a(n-3) - 84*a(n-4) + 96*a(n-5) - 96*a(n-6) + 128*a(n-7) - 64*a(n-8).
Empirical g.f.: 8*x^3*(1 - x)^2*(3 - 4*x) / (1 - 4*x + 2*x^2 - 8*x^3 + 8*x^4)^2. - Colin Barker, Feb 16 2019
EXAMPLE
Some solutions for n=4:
..0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..1. .0..0. .0..0
..2..0. .0..2. .0..1. .2..1. .2..1. .1..2. .1..0. .1..2. .1..2. .1..2
..1..0. .0..1. .0..2. .0..1. .1..0. .2..0. .0..2. .2..0. .0..2. .1..2
..1..2. .2..2. .1..1. .2..0. .0..2. .2..1. .1..1. .1..2. .2..0. .0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 15 2017
STATUS
approved