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%I A199143 #5 Mar 31 2012 12:36:35
%S A199143 1,3,13,65,393,2539,16866,113432,766473,5188597,35148945,238173743,
%T A199143 1614066774,10938730576,74134306725,502428413393,3405102418833,
%U A199143 23077383280435,156402287318610,1059984943413152,7183834447992225
%N A199143 Number of nX2 0..3 arrays with values 0..3 introduced in row major order and each element equal to one or two horizontal and vertical neighbors
%C A199143 Column 2 of A199149
%H A199143 R. H. Hardin, <a href="/A199143/b199143.txt">Table of n, a(n) for n = 1..200</a>
%F A199143 Empirical: a(n) = 7*a(n-1) +2*a(n-2) -16*a(n-3) -49*a(n-4) -35*a(n-5) +56*a(n-6) +54*a(n-7) +45*a(n-8) -27*a(n-9) for n>11
%e A199143 Some solutions for n=4
%e A199143 ..0..0....0..0....0..0....0..0....0..1....0..1....0..0....0..1....0..1....0..0
%e A199143 ..0..1....0..0....1..2....1..0....0..1....0..1....1..0....0..1....0..1....0..1
%e A199143 ..1..1....1..1....1..2....1..0....1..1....0..1....1..0....1..2....0..0....0..1
%e A199143 ..0..0....0..0....1..1....1..1....2..2....1..1....1..0....1..2....1..1....0..1
%K A199143 nonn
%O A199143 1,2
%A A199143 _R. H. Hardin_ Nov 03 2011

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