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A221134 Number of nX3 arrays of occupancy after each element moves to some horizontal or vertical neighbor, with no occupancy greater than 2.

%I A221134 #6 Jun 02 2025 08:11:10
%S A221134 2,49,656,12544,200072,3485689,58132316,990486784,16699002692,
%T A221134 282999528529,4783766470826,80965479678724,1369496232351362,
%U A221134 23171487659654569,391996208325992186,6631958618350959364
%N A221134 Number of nX3 arrays of occupancy after each element moves to some horizontal or vertical neighbor, with no occupancy greater than 2.
%C A221134 Column 3 of A221139
%H A221134 R. H. Hardin, <a href="/A221134/b221134.txt">Table of n, a(n) for n = 1..29</a>
%F A221134 Empirical: a(n) = 21*a(n-1) -1450*a(n-3) +4782*a(n-4) -372*a(n-5) +1450*a(n-6) +69*a(n-8) +a(n-9)
%e A221134 Some solutions for n=3
%e A221134 ..2..1..1....1..2..0....0..2..2....2..1..0....0..2..2....0..1..2....0..2..2
%e A221134 ..1..0..1....1..2..0....1..1..1....2..1..2....0..2..1....2..0..1....1..0..1
%e A221134 ..0..2..1....1..2..0....0..1..1....0..0..1....0..2..0....2..1..0....2..1..0
%K A221134 nonn
%O A221134 1,1
%A A221134 _R. H. Hardin_ Jan 02 2013