OFFSET
1,2
COMMENTS
Every 0 is next to 0 1's, every 1 is next to 1 3's, every 2 is next to 2 2's, every 3 is next to 3 4's, every 4 is next to 4 0's.
Column 5 of A196922.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) -5*a(n-2) -3*a(n-3) -14*a(n-4) +21*a(n-5) -55*a(n-6) -220*a(n-7) -191*a(n-8) -132*a(n-9) +188*a(n-10) +12*a(n-11) +165*a(n-12) +510*a(n-13) +814*a(n-14) +641*a(n-15) +80*a(n-16) -21*a(n-17) -118*a(n-18) +47*a(n-19) -4*a(n-20) +15*a(n-21) -7*a(n-22) for n>23.
EXAMPLE
Some solutions for n=4
..0..0..0..0..0....0..2..2..2..2....0..0..0..2..2....0..0..0..0..0
..0..4..0..2..2....0..2..0..0..2....0..0..0..2..2....0..4..0..4..0
..0..0..0..2..2....0..2..0..2..2....0..2..2..0..0....0..0..0..0..0
..0..0..0..0..0....0..2..2..2..0....0..2..2..0..0....0..0..0..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 07 2011
STATUS
approved