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Number of n-bead necklaces labeled with numbers -1..1 not allowing reversal, with sum zero with no three beads in a row equal.
1

%I #7 Mar 12 2017 23:21:53

%S 1,2,2,5,8,20,38,88,196,464,1088,2628,6344,15554,38318,95170,237536,

%T 596286,1503098,3805452,9668776,24650428,63035390,161648194,415589336,

%U 1071003162,2766083600,7158525512,18561001524,48210881198,125430649666

%N Number of n-bead necklaces labeled with numbers -1..1 not allowing reversal, with sum zero with no three beads in a row equal.

%C Column 1 of A208945.

%H R. H. Hardin, <a href="/A208938/b208938.txt">Table of n, a(n) for n = 1..33</a>

%e All solutions for n=5:

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

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

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

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

%e ..1....0....0....1....0....0....1....1

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 03 2012