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%I #5 Mar 31 2012 12:35:55
%S 1,1,7,21,169,635,3803,19013,115755,642065,4138291,25416351,165975915,
%T 1053686983,6884578761,44272817075,290607235917,1898355935879,
%U 12584064113799,83219457433335,554858908945825,3692717431924057
%N Number of strings of n numbers x(i) in -3..3 with sums of x(i) and of x(i)*x(i+1) both zero
%C Column 3 of A183944
%H R. H. Hardin, <a href="/A183938/b183938.txt">Table of n, a(n) for n = 1..41</a>
%e Some solutions for n=4
%e .-3....1...-2...-1...-1....0....0....3....0....0....1....0....1....3...-2...-1
%e ..0....0....0....0...-2....1...-1....0....2....3....2...-2....0....0....0....0
%e ..0....0....2....0....2....0....0...-3....0....0...-2....0...-1....0....0....1
%e ..3...-1....0....1....1...-1....1....0...-2...-3...-1....2....0...-3....2....0
%K nonn
%O 1,3
%A _R. H. Hardin_ Jan 08 2011
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