OFFSET
1,2
COMMENTS
Every 0 is next to 0 2's, every 1 is next to 1 3's, every 2 is next to 2 4's, every 3 is next to 3 1's, every 4 is next to 4 0's.
Column 3 of A196989.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) +2*a(n-2) +6*a(n-3) +11*a(n-4) +14*a(n-5) +4*a(n-6) -4*a(n-7) -4*a(n-8) -a(n-9).
Empirical g.f.: x*(1 + 2*x + 5*x^2 + 3*x^3 + 7*x^4 + 4*x^5 - 3*x^6 - 5*x^7 - 2*x^8) / (1 - x - 2*x^2 - 6*x^3 - 11*x^4 - 14*x^5 - 4*x^6 + 4*x^7 + 4*x^8 + x^9). - Colin Barker, May 11 2018
EXAMPLE
Some solutions for n=4:
..0..0..0....0..0..1....1..3..1....1..0..0....0..0..1....0..1..0....0..0..0
..0..1..0....0..1..3....0..1..1....3..1..1....1..1..3....1..3..1....0..0..1
..1..3..1....0..1..1....0..1..3....1..1..3....3..1..1....0..0..0....0..1..3
..0..0..0....1..3..1....0..0..1....0..0..1....1..0..0....0..0..0....0..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 08 2011
STATUS
approved