OFFSET
1,1
COMMENTS
Column 4 of A222838.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - a(n-3) for n>4.
Conjectures from Colin Barker, Aug 16 2018: (Start)
G.f.: x*(7 + 82*x + 10*x^2 - 17*x^3) / ((1 + x)*(1 - 3*x + x^2)).
a(n) = (3/5)*2^(2-n)*((-1)^n*2^(2+n) + (3-sqrt(5))^(1+n) + (3+sqrt(5))^(1+n)) for n>1.
(End)
EXAMPLE
Some solutions for n=4:
..0..0..1..1....0..1..2..3....0..1..1..2....0..1..1..2....0..0..1..2
..2..2..3..3....2..1..0..3....2..2..0..3....0..2..3..3....3..2..1..3
..3..1..0..2....2..3..0..1....1..3..0..1....3..2..0..1....1..2..0..3
..3..1..0..2....0..3..2..2....0..3..2..1....3..1..0..2....1..3..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 06 2013
STATUS
approved