A221870 - OEIS

%I #5 Jan 28 2013 04:12:21

%S 1,20,162,1442,12688,110720,970828,8489090,74301713,650080567,

%T 5688284025,49771429169,435493321644,3810502524152,33341324878142,

%U 291731631862014,2552608002906241,22334937934827800,195427359369424289

%N Number of nX2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without consecutive moves in the same direction

%C Column 2 of A221873

%H R. H. Hardin, <a href="/A221870/b221870.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 7*a(n-1) +27*a(n-2) -77*a(n-3) -247*a(n-4) +195*a(n-5) +277*a(n-6) -51*a(n-7) -32*a(n-8) +103*a(n-9) -78*a(n-10) +25*a(n-11) -4*a(n-12)

%e Some solutions for n=3

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 28 2013