OFFSET
1,2
COMMENTS
Every 0 is next to 0 4'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 0's.
Column 3 of A197217.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = 2*a(n-1) +8*a(n-3) +10*a(n-4) +16*a(n-5) +8*a(n-6) +6*a(n-7) -8*a(n-8) -12*a(n-9) -10*a(n-10) -4*a(n-11) -a(n-12).
Empirical g.f.: x*(1 + 3*x + 4*x^2 + 8*x^3 + 11*x^4 + 3*x^5 - x^6 - 5*x^7 - 14*x^8 - 10*x^9 - 5*x^10 - x^11) / (1 - 2*x - 8*x^3 - 10*x^4 - 16*x^5 - 8*x^6 - 6*x^7 + 8*x^8 + 12*x^9 + 10*x^10 + 4*x^11 + x^12). - Colin Barker, May 11 2018
EXAMPLE
Some solutions for n=4:
..0..1..0....0..0..0....0..0..0....1..3..1....0..0..0....2..2..0....2..2..0
..1..3..1....2..2..2....0..0..0....0..1..0....1..0..0....2..2..0....2..2..0
..2..2..0....2..0..2....0..2..2....0..0..0....3..1..0....0..0..0....0..1..0
..2..2..0....2..2..2....0..2..2....0..0..0....1..0..0....0..0..0....1..3..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 11 2011
STATUS
approved