A221404 - OEIS

%I #7 Jan 15 2013 07:32:21

%S 0,16,0,436,0,12668,0,368268,0,10705360,0,311197280,0,9046269888,0,

%T 262968117056,0,7644280337936,0,222213327464336,0,6459569820912704,0,

%U 187774705858714240,0,5458465675503960896,0,158673381440822516672,0

%N Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with every occupancy equal to zero or two

%C Column 3 of A221408

%H R. H. Hardin, <a href="/A221404/b221404.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 36*a(n-2) -200*a(n-4) -40*a(n-6) -84*a(n-8) +80*a(n-10) -20*a(n-12) +80*a(n-14)

%e Some solutions for n=4

%e ..0..2..0....2..0..2....2..0..2....0..2..0....0..2..0....2..0..0....0..2..2

%e ..2..0..0....2..0..0....0..0..2....0..0..2....0..2..0....0..2..2....0..0..0

%e ..2..2..2....0..0..2....0..0..2....2..2..2....2..0..2....0..0..0....2..0..2

%e ..0..2..0....2..2..0....2..0..2....0..0..2....2..0..2....2..2..2....2..2..0

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 15 2013