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%I #5 Mar 31 2012 12:36:37
%S 1,11,51,351,2031,13363,82555,536967,3409609,22163661,142744843,
%T 930121865,6040974735,39482258363,257848379869,1690142722447,
%U 11081263427471,72823380368573,478876538926483,3154101346620987
%N Number of -5..5 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative
%C Column 5 of A199898
%H R. H. Hardin, <a href="/A199895/b199895.txt">Table of n, a(n) for n = 1..200</a>
%e Some solutions for n=6
%e ..3...-2...-1...-2....0...-3....0...-1....3....4...-2...-2...-2...-5...-3...-2
%e .-5....2....4....5....4....1...-2....0...-5...-4....3....1....1....0....2....3
%e ..5...-4...-2...-4...-4...-3....3...-5....1....1...-2...-2...-3....2...-5....0
%e .-3....4....0....3....1....1...-2....2...-4....0....4....0....3....0....3...-5
%e ..1...-3....3...-5...-5....0....0....0....0...-1...-4....3....0....5...-1....4
%e .-1....3...-4....3....4....4....1....4....5....0....1....0....1...-2....4....0
%K nonn
%O 1,2
%A _R. H. Hardin_ Nov 11 2011
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