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%I #6 Aug 12 2016 06:54:16
%S 0,6,20,268,2324,28318,315196,3786836,45099306,547824556,6687936028,
%T 82350672500,1019550923830,12691867518330,158695413996448,
%U 1992293553570646,25099547132728742,317210539882144928
%N Number of 3Xn arrays containing n copies of 0..3-1 with every element equal to at least one horizontal or vertical neighbor and the top left element equal to 0.
%C Row 3 of A267901.
%H R. H. Hardin, <a href="/A267903/b267903.txt">Table of n, a(n) for n = 1..41</a>
%e Some solutions for n=4
%e ..0..2..1..1....0..0..2..2....0..0..1..1....0..2..2..1....0..0..1..1
%e ..0..2..0..2....2..2..1..0....2..1..1..0....0..0..0..1....2..0..1..1
%e ..1..1..0..2....1..1..1..0....2..2..2..0....1..1..2..2....2..0..2..2
%Y Cf. A267901.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 22 2016
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