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%I #7 Apr 16 2023 20:25:21
%S 25,325,1205,14477,100885,1171345,11535493,136061137,1540834589,
%T 18592832393,222616829157,2732659664405,33554957179729,
%U 416689678586229,5184974750699645,64895937068447245,813946908435419257
%N Number of arrangements of n+1 numbers x(i) in -6..6 with the sum of x(i)*x(i+1) equal to zero.
%C Column 6 of A188358.
%H R. H. Hardin, <a href="/A188355/b188355.txt">Table of n, a(n) for n = 1..27</a>
%e Some solutions for n=4
%e ..2...-3....1...-1...-6...-1....3...-6....1....2...-4...-3....1...-4....0...-2
%e ..0...-2...-5....3...-2....0....5....1...-2...-1....0...-5....4...-1....1...-6
%e ..6...-3...-1....3....6....2...-3....2...-3...-3...-5....3...-4....4....0...-1
%e ..0....6....5....6...-6...-2....0....1....1...-1....4....0....6....0...-1....6
%e .-5....1....1...-4...-6...-2....4....2...-1....4....5...-3....6...-2....0...-2
%Y Cf. A188358.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 28 2011
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