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 3 of A196210.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) - 2*a(n-4) + 3*a(n-5) - 2*a(n-6) + 2*a(n-7) - 2*a(n-8) + a(n-9).
Empirical g.f.: x*(4 - 4*x - 9*x^2 + 9*x^3 - 3*x^4 + 8*x^5 - 7*x^6 + x^7 + 2*x^8) / ((1 - x)*(1 - x - x^3)*(1 - x - x^2 + x^4 - x^5)). - Colin Barker, Mar 01 2018
EXAMPLE
Some solutions for n=4:
..1..1..0....1..0..0....1..0..1....1..0..0....1..1..1....1..1..1....0..0..0
..0..1..1....1..0..0....1..0..1....1..1..1....0..0..0....0..0..0....0..0..0
..0..1..1....1..0..0....1..0..1....0..1..1....0..0..0....0..0..0....0..0..0
..1..1..0....1..0..0....1..0..1....1..1..0....0..0..0....1..1..1....1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 29 2011
STATUS
approved