OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 12*a(n-2) - 18*a(n-3) - 29*a(n-4) + 19*a(n-5) + 38*a(n-6) + 8*a(n-7).
Empirical g.f.: 2*x*(2 + 4*x - 8*x^2 - 13*x^3 + 8*x^4 + 19*x^5 + 4*x^6) / (1 - 3*x - 12*x^2 + 18*x^3 + 29*x^4 - 19*x^5 - 38*x^6 - 8*x^7). - Colin Barker, Oct 26 2018
EXAMPLE
Some solutions for n=5:
..1..3..1..0..0....1..3..3..0..1....3..1..1..3..1....1..3..1..0..3
..2..3..0..0..3....1..0..0..0..2....3..1..2..3..0....2..0..1..0..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 23 2014
STATUS
approved