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A183326 Number of n X 5 binary arrays with each 1 adjacent to exactly two other 1s.

%I A183326 #11 May 01 2019 14:04:09
%S A183326 1,6,19,72,289,996,3325,11415,39720,138689,483837,1682961,5845649,
%T A183326 20310166,70604782,245504404,853649448,2967979455,10318546476,
%U A183326 35873587105,124720541039,433616480871,1507558685202,5241330944265
%N A183326 Number of n X 5 binary arrays with each 1 adjacent to exactly two other 1s.
%H A183326 R. H. Hardin, <a href="/A183326/b183326.txt">Table of n, a(n) for n = 1..200</a>
%H A183326 Robert Israel, <a href="/A183326/a183326.pdf">Maple-assisted proof of empirical g.f.</a>
%F A183326 Empirical: a(n)=5*a(n-1)-8*a(n-2)+9*a(n-3)-2*a(n-4)+14*a(n-5)+3*a(n-6)-44*a(n-7)+18*a(n-8)+29*a(n-9)-10*a(n-10)-69*a(n-11)+16*a(n-12)+87*a(n-13)+15*a(n-14)-55*a(n-15)-40*a(n-16)+6*a(n-17)+9*a(n-18)+4*a(n-19)-2*a(n-20).
%F A183326 Empirical formula verified (see link). - _Robert Israel_, May 01 2019
%e A183326 Some solutions for 7X5
%e A183326 ..0..1..1..1..1....0..1..1..0..0....1..1..0..1..1....0..0..1..1..1
%e A183326 ..1..1..0..0..1....0..1..1..0..0....1..1..0..1..1....1..1..1..0..1
%e A183326 ..1..0..0..1..1....0..0..0..0..0....0..0..0..0..0....1..0..0..0..1
%e A183326 ..1..0..0..1..0....0..0..1..1..1....0..1..1..1..0....1..1..0..1..1
%e A183326 ..1..0..0..1..0....0..1..1..0..1....0..1..0..1..1....0..1..0..1..0
%e A183326 ..1..1..0..1..0....0..1..0..1..1....0..1..0..0..1....0..1..0..1..0
%e A183326 ..0..1..1..1..0....0..1..1..1..0....0..1..1..1..1....0..1..1..1..0
%Y A183326 Column 5 of A183328.
%K A183326 nonn
%O A183326 1,2
%A A183326 _R. H. Hardin_, Jan 03 2011