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Half the number of n X 3 binary arrays with the number of 1-1 adjacencies equal to the number of 0-0 adjacencies.
1

%I #8 Mar 08 2023 12:45:49

%S 1,6,25,164,1092,7954,57519,429936,3205504,24288784,184062519,

%T 1407419548,10773952376,82925706270,639182387805,4944237734904,

%U 38299501221912,297409232997320,2312508964364352,18013343447396448,140477702503827052

%N Half the number of n X 3 binary arrays with the number of 1-1 adjacencies equal to the number of 0-0 adjacencies.

%C Column 3 of A183253.

%H R. H. Hardin, <a href="/A183249/b183249.txt">Table of n, a(n) for n = 1..100</a>

%e Some solutions with a(1,1)=0 for 3 X 3

%e ..0..1..1....0..1..1....0..0..0....0..1..0....0..1..0....0..0..1....0..1..0

%e ..0..1..0....0..0..1....1..1..1....0..1..0....0..1..1....0..0..1....1..1..0

%e ..0..1..0....1..0..1....0..0..1....0..1..1....0..0..1....1..1..1....1..0..0

%Y Cf. A183253.

%K nonn

%O 1,2

%A _R. H. Hardin_, Jan 03 2011