OFFSET
1,1
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) + 14*a(n-3) + 18*a(n-4) - 8*a(n-5) + 16*a(n-6) + 80*a(n-7) - 32*a(n-8) - 64*a(n-9) for n>10.
Empirical g.f.: x*(3 + 24*x + 36*x^2 + 70*x^3 + 18*x^4 - 48*x^5 + 112*x^6 + 208*x^7 - 160*x^8 - 192*x^9) / (1 - 4*x - 4*x^2 - 14*x^3 - 18*x^4 + 8*x^5 - 16*x^6 - 80*x^7 + 32*x^8 + 64*x^9). - Colin Barker, Jan 31 2019
EXAMPLE
Some solutions for n=4:
..0..1..2. .0..0..1. .0..1..1. .0..0..1. .0..0..1. .0..0..1. .0..0..1
..2..2..1. .0..0..2. .1..1..2. .0..0..1. .0..1..2. .1..0..2. .2..0..1
..2..2..0. .2..2..1. .1..1..0. .0..1..1. .2..1..1. .1..2..2. .0..2..1
..0..1..1. .0..2..1. .2..0..0. .1..2..2. .1..1..0. .1..0..2. .1..1..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jul 16 2016
STATUS
approved