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 3's, every 3 is next to 3 4's, every 4 is next to 4 1's.
Column 2 of A196210.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-4) - a(n-5).
Empirical g.f.: x*(1 + x + x^2)*(3 - 4*x - x^2) / ((1 - x - x^2)*(1 - x - x^3)). - Colin Barker, Mar 01 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..1....1..0....1..0....0..1....0..0....1..1....1..0....0..1....0..0
..0..0....0..1....1..0....1..1....0..1....1..1....0..0....1..0....1..1....0..0
..0..0....1..1....1..1....0..1....0..1....1..1....0..0....1..0....1..0....0..0
..1..1....1..0....0..1....0..1....0..1....0..0....0..0....1..0....1..0....0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 29 2011
STATUS
approved