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 0's, every 4 is next to 4 0's
Column 3 of A198185
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..200
FORMULA
Empirical: a(n) = a(n-1) +3*a(n-2) -a(n-3) +3*a(n-4) +14*a(n-5) -a(n-6) -13*a(n-7) -17*a(n-8) -43*a(n-9) -73*a(n-10) -111*a(n-11) -70*a(n-12) -49*a(n-13) +87*a(n-14) +274*a(n-15) +424*a(n-16) +337*a(n-17) +389*a(n-18) +202*a(n-19) +184*a(n-20) -420*a(n-21) -643*a(n-22) -580*a(n-23) -287*a(n-24) -116*a(n-25) -426*a(n-26) -5*a(n-27) +80*a(n-28) +414*a(n-29) +294*a(n-30) +24*a(n-31) -12*a(n-32) -72*a(n-33) -30*a(n-34) +4*a(n-36) +4*a(n-37)
EXAMPLE
Some solutions for n=4
..1..2..1....2..1..0....2..1..0....0..1..2....0..3..0....1..2..1....2..1..0
..0..3..0....1..0..1....1..1..2....2..1..1....3..0..3....1..2..1....1..0..3
..3..0..1....1..2..2....0..1..1....1..1..0....0..3..0....1..2..1....0..3..0
..0..1..2....0..1..1....1..2..0....0..2..1....1..2..1....1..2..1....1..2..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin Oct 21 2011
STATUS
approved