OFFSET
1,1
COMMENTS
Column 2 of A218084.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
Todd Mullen, On Variants of Diffusion, Dalhousie University (Halifax, NS Canada, 2020).
FORMULA
Empirical: a(n) = a(n-1) + 2*a(n-2) + a(n-3).
Empirical g.f.: 2*x*(1 + x) / (1 - x - 2*x^2 - x^3). - Colin Barker, Jul 24 2018
EXAMPLE
All solutions for n=3:
..1..1....0..0....0..0....1..1....0..0....0..0....1..0....1..1
..0..0....0..0....0..0....1..0....0..0....0..1....0..0....1..1
..0..0....1..1....0..0....0..0....0..1....1..1....0..0....1..1
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 20 2012
STATUS
approved