OFFSET
1,2
COMMENTS
Every 0 is next to 0 0's, every 1 is next to 1 2's, every 2 is next to 2 1's, every 3 is next to 3 3's, every 4 is next to 4 4's
Column 3 of A196138
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) +3*a(n-4) +3*a(n-5) +6*a(n-6) -5*a(n-7) -14*a(n-8) -17*a(n-9) -32*a(n-10) -25*a(n-11) -38*a(n-12) -11*a(n-13) +19*a(n-14) +39*a(n-15) +42*a(n-16) +6*a(n-17) +18*a(n-18) +20*a(n-19) +32*a(n-20) +24*a(n-21)
EXAMPLE
Some solutions for n=4
..1..1..2....0..1..2....1..1..2....1..2..1....0..1..2....2..1..1....0..1..2
..2..1..1....2..1..1....2..0..1....1..2..1....1..0..1....1..1..2....1..0..1
..2..1..1....1..1..0....1..1..0....1..2..1....2..1..1....1..1..2....2..2..1
..1..1..2....0..2..1....0..2..1....1..2..1....0..1..2....2..1..1....1..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Sep 28 2011
STATUS
approved