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A185535 1/6 the number of n X 2 0..5 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

%I A185535 #11 Apr 16 2018 09:06:17
%S A185535 1,11,110,1155,12105,127190,1336205,14039455,147510990,1549891055,
%T A185535 16284627805,171101820790,1797758782905,18888967243155,
%U A185535 198465493076590,2085267630701755,21909809227375505,230205338311698390
%N A185535 1/6 the number of n X 2 0..5 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
%C A185535 Column 2 of A185540.
%H A185535 R. H. Hardin, <a href="/A185535/b185535.txt">Table of n, a(n) for n = 1..200</a>
%F A185535 Empirical: a(n) = 9*a(n-1) + 19*a(n-2) - 25*a(n-3) - 75*a(n-4) - 125*a(n-5).
%F A185535 Empirical g.f.: x*(1 + 2*x - 8*x^2 - 19*x^3 - 30*x^4) / (1 - 9*x - 19*x^2 + 25*x^3 + 75*x^4 + 125*x^5). - _Colin Barker_, Apr 16 2018
%e A185535 Some solutions for 3 X 2 with a(1,1)=0:
%e A185535 ..0..4....0..0....0..0....0..0....0..0....0..0....0..3....0..5....0..0....0..5
%e A185535 ..0..4....5..1....0..5....1..1....1..3....0..2....0..3....0..5....2..0....0..5
%e A185535 ..0..4....5..1....0..5....3..3....1..3....2..2....3..3....3..3....2..0....5..5
%Y A185535 Cf. A185540.
%K A185535 nonn
%O A185535 1,2
%A A185535 _R. H. Hardin_, Jan 30 2011