OFFSET
1,1
COMMENTS
Column 2 of A223062.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 18*a(n-1) - 71*a(n-2) + 102*a(n-3) - 48*a(n-4) for n>5.
Empirical g.f.: x*(2 - 26*x + 76*x^2 - 73*x^3 + 16*x^4) / ((1 - x)*(1 - 2*x)*(1 - 15*x + 24*x^2)). - Colin Barker, Aug 16 2018
EXAMPLE
Some solutions for n=3:
..0..1....0..1....0..1....0..1....0..0....0..1....0..1....0..1....0..1....0..0
..2..3....2..0....2..2....2..1....1..2....1..0....1..2....2..3....2..3....1..1
..3..2....0..2....0..3....0..3....2..3....2..0....0..1....3..0....2..1....0..2
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 13 2013
STATUS
approved