OFFSET
1,4
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 6*a(n-2) + 32*a(n-4) - 20*a(n-5) + 24*a(n-6) - 16*a(n-7).
Empirical g.f.: 4*x^4*(1 - 3*x + 2*x^2 - 4*x^3) / (1 - 3*x - 6*x^2 - 32*x^4 + 20*x^5 - 24*x^6 + 16*x^7). - Colin Barker, Sep 25 2018
EXAMPLE
All solutions for n=4:
..0..2..2..0....0..2..1..0....0..1..1..0....0..1..2..0
..0..1..1..0....0..1..2..0....0..2..2..0....0..2..1..0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 03 2013
STATUS
approved