OFFSET
1,1
COMMENTS
Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 0's, every 4 is next to 4 0's.
Column 2 of A197537.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-3) - 4*a(n-4) - 3*a(n-5) + a(n-7) + a(n-8).
Empirical g.f.: x*(1 + x)^2*(3 - 6*x - 2*x^2 - 2*x^3 + x^4 + 2*x^5) / ((1 - x - x^2 - x^3)*(1 - 2*x - x^2 - x^3 + x^5)). - Colin Barker, Mar 02 2018
EXAMPLE
Some solutions for n=4:
..1..0....1..0....0..1....1..0....1..1....2..1....0..0....0..1....2..1....0..0
..1..0....2..1....1..1....1..1....0..0....1..0....0..0....1..1....1..0....0..3
..1..1....2..1....1..0....0..1....0..3....1..0....0..0....1..0....1..1....0..0
..0..1....1..0....1..0....1..2....0..0....2..1....1..1....2..1....0..1....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 16 2011
STATUS
approved