OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 9*a(n-1) - 16*a(n-2) + 9*a(n-3) - 12*a(n-4) + 5*a(n-5) + 7*a(n-6) - 4*a(n-7).
Empirical g.f.: x^2*(3 - 2*x)*(1 - x + x^2)^2 / (1 - 9*x + 16*x^2 - 9*x^3 + 12*x^4 - 5*x^5 - 7*x^6 + 4*x^7). - Colin Barker, Feb 08 2019
EXAMPLE
Some solutions for n=4:
..0..1..2..3. .0..2..3..2. .0..2..1..0. .0..1..2..1. .0..1..0..2
..3..2..1..0. .1..1..0..2. .1..3..2..1. .3..1..3..0. .1..2..3..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 14 2016
STATUS
approved