%I #4 Sep 24 2012 09:00:57
%S 2,121,3456,108900,3356150,103754596,3204762800,99000846736,
%T 3058191082836,94469768837136,2918234843229824,90146267379942400,
%U 2784679492865603384,86020644174498694144,2657236212002608395264
%N Number of city-block distance 1, pressure limit 2 movements in an nX3 array with each element moving exactly one horizontally or vertically and no element acquiring more than two neighbors
%C Column 3 of A217028
%H R. H. Hardin, <a href="/A217023/b217023.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 33*a(n-1) -2152*a(n-3) +3498*a(n-4) +26598*a(n-5) -55952*a(n-6) +44616*a(n-8) -17576*a(n-9) for n>10
%e Some solutions for n=3 (movement: 0=n 1=e 2=s 3=w)
%e ..1..1..2....1..1..2....2..2..3....1..3..2....1..1..2....2..1..3....1..2..3
%e ..2..3..3....0..2..3....2..3..0....0..1..3....1..0..2....0..1..2....2..2..0
%e ..0..1..3....0..0..0....1..3..3....0..0..3....1..3..3....0..3..3....0..3..0
%K nonn
%O 1,1
%A _R. H. Hardin_ Sep 24 2012