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Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2
1

%I #4 Jan 06 2013 19:52:27

%S 4,81,2116,58081,1612900,44903401,1250753956,34842328921,970622980804,

%T 27039303204489,753252725702500,20983889126032561,584562920742585316,

%U 16284579460194091201,453650957002812576484,12637673040690140943889

%N Number of nX4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2

%C Column 4 of A221255

%H R. H. Hardin, <a href="/A221251/b221251.txt">Table of n, a(n) for n = 1..23</a>

%F Empirical: a(n) = 39*a(n-1) -356*a(n-2) +1365*a(n-3) -2739*a(n-4) +2904*a(n-5) -1683*a(n-6) +573*a(n-7) -116*a(n-8) +15*a(n-9) -a(n-10)

%e Some solutions for n=3

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Jan 06 2013