OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 7*a(n-1) - 3*a(n-2) + 27*a(n-3) + 28*a(n-4) + 14*a(n-5) - 8*a(n-6) - 8*a(n-7) for n>8.
Empirical g.f.: 2*x^2*(3 + 18*x - 32*x^2 - 43*x^3 - 26*x^4 + 10*x^5 + 12*x^6) / (1 - 7*x + 3*x^2 - 27*x^3 - 28*x^4 - 14*x^5 + 8*x^6 + 8*x^7). - Colin Barker, Sep 28 2018
EXAMPLE
Some solutions for n=4:
..0..1..0..1....0..3..2..1....0..3..2..1....0..1..2..1....0..3..0..3
..2..3..2..1....0..1..0..1....2..1..0..1....2..3..2..3....2..1..2..1
..0..1..0..3....2..3..2..1....0..3..2..3....0..1..0..1....0..1..0..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 06 2013
STATUS
approved