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%I #6 Mar 31 2012 12:36:37
%S 1,4,10,26,68,178,472,1276,3462,9496,26024,71956,198740,552814,
%T 1535556,4290252,11968194,33553214,93917400,264020106,741024426,
%U 2087799972,5872999754,16577458520,46720454112,132081262316,372843051320
%N Number of -2..2 arrays x(0..n-1) of n elements with zero sum and elements alternately strictly increasing and strictly decreasing
%C Column 2 of A200057
%H R. H. Hardin, <a href="/A200051/b200051.txt">Table of n, a(n) for n = 1..200</a>
%e Some solutions for n=6
%e .-1...-1....0....2....0....0....0....0....0...-2....0....0....1...-1...-2...-2
%e ..1...-2...-1....1....1...-1....1....1...-1....1....2...-2....2....1....1....1
%e ..0....2....0....2...-2....2...-2...-1....1...-1...-2....0...-2....0....0...-1
%e ..2...-2...-1...-2....0...-2....1....0....0....1....0...-1....2....1....1....1
%e .-2....2....2...-1...-1....1...-2...-2....1....0...-1....2...-2...-1...-2...-1
%e ..0....1....0...-2....2....0....2....2...-1....1....1....1...-1....0....2....2
%K nonn
%O 1,2
%A _R. H. Hardin_ Nov 13 2011
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