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%I #6 Mar 31 2012 12:36:36
%S 1,4,18,72,320,1414,6346,28766,131246,602390,2777638,12857572,
%T 59712940,278096674,1298309782,6074112952,28470828008,133671581490,
%U 628526085270,2959291856816,13950087683416,65832860408434,310987879638926
%N Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no two consecutive zero elements
%C Column 2 of A199530
%H R. H. Hardin, <a href="/A199524/b199524.txt">Table of n, a(n) for n = 1..200</a>
%e Some solutions for n=5
%e .-1....2....0...-1...-1....1...-2....2....1....1....0....0...-2....0...-1...-1
%e ..0....1...-2....2....2....1....2...-2....0....2...-1....1....1....1....0...-2
%e .-2...-2....1....2....2....1...-2....2....1...-1...-1....1....2...-2....2....0
%e ..1...-1....0...-2...-1...-2....2....0...-2....0....0...-1....1....2....1....2
%e ..2....0....1...-1...-2...-1....0...-2....0...-2....2...-1...-2...-1...-2....1
%K nonn
%O 1,2
%A _R. H. Hardin_ Nov 07 2011
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