%I #5 Jan 15 2013 20:05:19
%S 0,10,0,150,0,2250,0,33750,0,506250,0,7593750,0,113906250,0,
%T 1708593750,0,25628906250,0,384433593750,0,5766503906250,0,
%U 86497558593750,0,1297463378906250,0,19461950683593750,0,291929260253906250,0
%N Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with every occupancy equal to zero or two
%C Column 3 of A221419
%H R. H. Hardin, <a href="/A221414/b221414.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 15*a(n-2)
%e Some solutions for n=4
%e ..0..2..0....2..2..0....0..2..2....2..0..0....2..2..0....2..0..0....0..2..2
%e ..2..2..0....0..2..0....0..2..0....0..2..2....0..0..2....0..2..0....0..2..0
%e ..2..2..0....2..0..2....0..2..0....2..0..0....2..0..0....2..2..0....2..0..0
%e ..0..0..2....0..2..0....2..2..0....0..2..2....2..2..0....2..2..0....2..2..0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 15 2013