A221657 - OEIS

%I #4 Jan 21 2013 11:40:55

%S 0,12,230,5879,128076,2853634,63318470,1408047450,31296772948,

%T 695652396949,15461913567744,343664536672236,7638450184626910,

%U 169775851711606490,3773518891128106982,83872027453458936923

%N Number of 3Xn arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without move-in move-out left turns

%C Row 3 of A221655

%H R. H. Hardin, <a href="/A221657/b221657.txt">Table of n, a(n) for n = 1..26</a>

%e Some solutions for n=3

%e ..1..2..0....0..2..2....0..3..1....0..1..0....0..2..2....1..0..1....1..1..0

%e ..0..0..1....0..3..1....0..1..1....0..3..2....0..2..0....0..3..0....0..3..0

%e ..1..4..0....0..1..0....0..2..1....1..2..0....1..2..0....1..3..0....2..2..0

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 21 2013