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%I #4 Mar 31 2012 12:36:11
%S 140,16272,355396,2880240,14715004,55994544,168083116,445304272,
%T 1033172284,2215496776,4323822892
%N Number of arrangements of 9 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero
%C Row 7 of A188249
%e Some solutions for n=4
%e .-4...-2...-3...-4...-3...-3...-4...-3...-4...-3...-3...-3...-2...-2...-4...-4
%e .-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4
%e .-2....1....3....1....1....1....1....1....1...-3....4....2...-4...-3...-2....3
%e .-1....1...-4....2...-1....3...-4...-1...-2....2....1....2...-4...-4....3....4
%e .-4...-3...-3...-1...-1...-1....4....3...-1...-2....3...-1....3....2...-1...-1
%e ..3....4...-3....3...-2....4....2...-4....1....1...-2...-3...-1...-3...-2....4
%e .-1....3....1...-2....3...-1....3...-2....3...-4...-1....2....4....4....4....2
%e ..3....2....2....3...-1...-4...-3....1...-2....4....1...-3...-3...-1...-3...-4
%e .-4...-4...-4....1....1....1...-1....2....4....2....2...-1....3....2...-1....2
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 25 2011
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