OFFSET
1,3
COMMENTS
Every 0 is next to 0 0's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 1's, every 4 is next to 4 4's.
Column 2 of A196078.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-2) +a(n-3) +2*a(n-5).
Empirical g.f.: x^2*(1 + 2*x - x^2 + 3*x^3) / (1 - x^2 - x^3 - 2*x^5). - Colin Barker, May 08 2018
EXAMPLE
All solutions for n=5:
..2..2....2..2....1..0....1..0....0..1....0..1
..2..2....2..2....3..1....3..1....1..3....1..3
..0..1....1..0....1..1....1..0....0..1....1..1
..1..3....3..1....1..3....2..2....2..2....3..1
..0..1....1..0....0..1....2..2....2..2....1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 27 2011
STATUS
approved