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Number of nX3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without 2-loops
1

%I #5 Jan 11 2013 21:02:38

%S 0,18,370,6893,122690,2152076,37541550,653557217,11369057766,

%T 197715942522,3438053202520,59781409121813,1039472974649122,

%U 18074147498877660,314268989617804842,5464430347020252629

%N Number of nX3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without 2-loops

%C Column 3 of A221351

%H R. H. Hardin, <a href="/A221348/b221348.txt">Table of n, a(n) for n = 1..22</a>

%F Empirical: a(n) = 26*a(n-1) -162*a(n-2) +198*a(n-3) +305*a(n-4) -794*a(n-5) +668*a(n-6) -244*a(n-7) +72*a(n-8)

%e Some solutions for n=3

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 11 2013