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A199896 Number of -6..6 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

%I A199896 #7 Jul 22 2025 13:26:14
%S A199896 1,13,67,545,3573,27457,193689,1462859,10651367,80142549,593254327,
%T A199896 4466635929,33386730231,251884546233,1894568061637,14327147198653,
%U A199896 108231414777793,820328179730055,6216861991058925,47216885967426099
%N A199896 Number of -6..6 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.
%C A199896 Column 6 of A199898
%H A199896 R. H. Hardin, <a href="/A199896/b199896.txt">Table of n, a(n) for n = 1..200</a>
%e A199896 Some solutions for n=6
%e A199896 .-5....3....5...-3...-2....2....2....2...-5....2....0....0...-6....0...-1...-2
%e A199896 ..2....0...-4....2....3....0...-5...-3....5...-2....1...-3....5...-2....3....2
%e A199896 .-2....4....2....0....0....2....5....2...-3....3...-5....6....0....3...-6...-3
%e A199896 ..6...-4...-5....0...-1...-2...-4...-4....0...-6....5...-2...-2...-1....3....0
%e A199896 ..0....0....4....6....1....2....6....4...-1....6...-1....3....0....6...-4....3
%e A199896 .-1...-3...-2...-5...-1...-4...-4...-1....4...-3....0...-4....3...-6....5....0
%K A199896 nonn
%O A199896 1,2
%A A199896 _R. H. Hardin_ Nov 11 2011