OFFSET
1,4
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 6*a(n-1) - a(n-2) - 12*a(n-3) + 20*a(n-4) + 24*a(n-5).
Empirical g.f.: 36*x^3 / ((1 + x)*(1 - 7*x + 8*x^2 + 4*x^3 - 24*x^4)). - Colin Barker, Sep 21 2018
EXAMPLE
Some solutions for n=4:
..0..1..2..0....0..0..1..0....0..1..0..0....0..1..1..0....0..2..2..0
..0..2..1..0....2..1..0..2....2..0..1..2....1..2..2..0....0..1..1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 20 2013
STATUS
approved