OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - 13*a(n-2) + 12*a(n-3) - 4*a(n-4) for n>7.
Empirical g.f.: x*(70 + 124*x - 1597*x^2 + 2754*x^3 - 1215*x^4 - 92*x^5 + 156*x^6) / ((1 - x)^2*(1 - 2*x)^2). - Colin Barker, Sep 19 2018
EXAMPLE
Some solutions for n=3:
..0..1..0..1..2..1....0..1..2..1..0..1....0..1..0..1..0..2....0..1..0..2..0..2
..2..3..2..3..0..3....2..3..0..3..2..3....3..2..3..2..3..3....3..2..3..1..3..1
..1..0..1..0..2..1....0..1..2..1..0..3....0..1..0..1..0..2....0..1..0..2..0..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 26 2013
STATUS
approved