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Number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of floor(x(i)/x(i+1)) equal to zero
1

%I #5 Mar 31 2012 12:36:15

%S 2,12,42,136,550,1892,7384,26816,103288,386928,1485566,5654000,

%T 21736466,83448592,321767288,1241835856,4803432344,18605438864,

%U 72168550344,280295950240,1089835505354,4242072071396,16526909026016,64446293812896

%N Number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of floor(x(i)/x(i+1)) equal to zero

%C Column 2 of A189498

%H R. H. Hardin, <a href="/A189491/b189491.txt">Table of n, a(n) for n = 1..200</a>

%e Some solutions for n=5

%e ..1....2....2....2....1...-2....1...-1....1....2...-1....1...-1....1....1...-1

%e ..2....1...-2...-1...-2...-1...-2...-2....1....2...-1...-2....1....2...-2....2

%e ..2....1...-1...-2...-2....2....2...-1...-1...-1...-2....1....1...-2...-2...-2

%e .-2...-1....2...-1....2....2....1....1....2...-1....2....2...-2....2....1...-1

%e .-2....1....2...-1...-2...-2...-1....2....1....2...-2....2...-1....1....1....1

%e ..2...-1...-2....2...-1....2...-1...-2...-2....2...-2....1....1....2....1....1

%K nonn

%O 1,1

%A _R. H. Hardin_ Apr 23 2011