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%I #4 Dec 09 2012 08:26:32
%S 4,31,139,1411,9430,63154,452515,3130768,21630714,150540232,
%T 1043064746,7226190511,50094800811,347052655839,2404198149909,
%U 16655726484462,115373519626103,799165840938429,5535587924914620,38342402997836989
%N Equals one maps: number of nX3 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and vertical neighbors in a random 0..1 nX3 array
%C Column 3 of A220287
%H R. H. Hardin, <a href="/A220284/b220284.txt">Table of n, a(n) for n = 1..21</a>
%e Some solutions for n=3
%e ..0..0..1....1..0..1....1..1..0....0..0..0....1..0..1....1..0..0....0..1..0
%e ..0..0..1....1..0..1....1..0..1....0..0..0....0..0..0....0..0..1....0..0..0
%e ..1..1..0....0..1..0....1..0..0....0..1..0....0..0..0....0..0..1....0..0..0
%K nonn
%O 1,1
%A _R. H. Hardin_ Dec 09 2012
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