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A185820 1/5 the number of nX4 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

%I A185820 #9 Jul 22 2025 10:02:05
%S A185820 5,656,49036,4443292,378212944,32995092992,2852526229300,
%T A185820 247462638659680,21440004040979204,1858466937288261508,
%U A185820 161065823451839652032,13959918564726559991320,1209903218593886396425592
%N A185820 1/5 the number of nX4 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
%C A185820 Column 4 of A185825
%H A185820 R. H. Hardin, <a href="/A185820/b185820.txt">Table of n, a(n) for n = 1..106</a>
%e A185820 Some solutions for 6X4 with a(1,1)=0
%e A185820 ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
%e A185820 ..0..1..1..0....0..1..1..0....0..1..1..0....0..1..1..0....0..1..1..0
%e A185820 ..3..0..0..0....3..0..0..0....1..0..0..0....1..0..0..0....0..0..0..0
%e A185820 ..3..1..1..2....3..3..2..2....1..2..2..2....1..1..2..2....2..1..2..2
%e A185820 ..4..0..0..2....4..3..1..1....1..0..0..2....3..2..2..1....2..1..4..4
%e A185820 ..4..2..2..2....4..3..3..3....1..4..4..2....3..3..1..1....3..3..2..2
%K A185820 nonn
%O A185820 1,1
%A A185820 _R. H. Hardin_ Feb 05 2011