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A183937 Number of strings of n numbers x(i) in -2..2 with sums of x(i) and of x(i)*x(i+1) both zero 1

%I

%S 1,1,5,15,81,237,1015,3891,16171,66237,297003,1304467,5981617,

%T 27407859,126441771,584452845,2721978059,12719931479,59862174023,

%U 282898499059,1341705275365,6380905008633,30422523202843,145340620435425

%N Number of strings of n numbers x(i) in -2..2 with sums of x(i) and of x(i)*x(i+1) both zero

%C Column 2 of A183944

%H R. H. Hardin, <a href="/A183937/b183937.txt">Table of n, a(n) for n = 1..81</a>

%e All solutions for n=4

%e ..1....0...-1....1....0...-2....0....1....2....2...-1....0....0...-1...-2

%e ..0...-1....0....2...-2....0....0....0....0....0....0....2....1...-2....0

%e ..0....0....0...-2....0....0....0...-1....0...-2....1....0....0....2....2

%e .-1....1....1...-1....2....2....0....0...-2....0....0...-2...-1....1....0

%K nonn

%O 1,3

%A _R. H. Hardin_ Jan 08 2011

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Last modified September 25 05:14 EDT 2021. Contains 347652 sequences. (Running on oeis4.)