OFFSET
1,2
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 2*a(n-1) + 9*a(n-4) - 18*a(n-5) - 14*a(n-8) + 28*a(n-9) + a(n-12) - 2*a(n-13).
Empirical g.f.: x*(1 - 2*x^3 - 12*x^4 + 7*x^7 + 25*x^8 - x^11 - 2*x^12) / ((1 - 2*x)*(1 + x^2 - 4*x^4 + x^6)*(1 - x^2 - 4*x^4 - x^6)). - Colin Barker, Jan 01 2019
EXAMPLE
All solutions for n=4:
..0..0....2..3....2..3....0..0....0..0....0..0
..0..0....0..0....2..3....2..3....0..0....2..3
..0..0....2..3....2..3....0..0....2..3....2..3
..0..0....0..0....2..3....2..3....0..0....2..3
..0..0....0..0....0..0....0..0....2..3....2..3
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 18 2015
STATUS
approved