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%I #8 Oct 19 2012 11:58:11
%S 3,8,22,72,280,1152,4632,17888,67232,251136,947136,3625216,14033664,
%T 54599680,212521344,826308096,3211280896,12490338304,48666153984,
%U 189986959360,742894424064,2908269379584,11394480500736,44672464896000
%N 1/4 the number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of sign(x(i))*(|x(i)| mod x(i+1)) equal to zero
%C Column 2 of A189951
%H R. H. Hardin, <a href="/A189944/b189944.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: (n+1)*a(n) = 4*(2*n+1)*a(n-1) - 24*n*a(n-2) + 16*(2*n-1)*a(n-3). - _Vaclav Kotesovec_, Oct 19 2012
%e Some solutions with n=3
%e ..2....2....2....1...-2...-2....1....2....2....1....2...-2...-2...-2...-1...-2
%e ..2....2....2....2....2...-2...-2....2...-2....1....2....2....2...-2....2...-2
%e ..2...-2...-2...-1...-1....1...-1...-1....2...-1...-2....2...-1....2....1...-1
%e ..2...-1...-2....2....1....1....2....1...-2...-1....2...-2...-1....1....2...-1
%K nonn
%O 1,1
%A _R. H. Hardin_ May 02 2011
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