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%I
%S 0,2,2,8,16,52,152,484,1536,5064,16946,57528,197616,686588,2407538,
%T 8510428,30300268,108575996,391301260,1417520988,5159160792,
%U 18857230104,69193592020,254802169904,941383915572,3488574124056,12964318919492
%N Number of strictly increasing arrangements of n nonzero numbers in -n..n with sum zero
%C Column 2 of A188122
%H R. H. Hardin, <a href="/A188115/b188115.txt">Table of n, a(n) for n = 1..31</a>
%e Some solutions for n=6
%e .-5...-5...-6...-6...-5...-6...-6...-6...-6...-5...-6...-4...-6...-6...-5...-6
%e .-4...-4...-4...-5...-4...-5...-5...-3...-4...-3...-5...-3...-4...-2...-4...-4
%e .-1...-1...-2...-1...-2...-4...-3...-2...-1...-1...-1...-1...-2...-1...-2...-1
%e ..1....1....2....3....2....4....3....2....2....2....2....1....3....1....1....2
%e ..4....3....4....4....4....5....5....3....3....3....4....2....4....2....4....4
%e ..5....6....6....5....5....6....6....6....6....4....6....5....5....6....6....5
%K nonn
%O 1,2
%A _R. H. Hardin_ Mar 21 2011
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