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Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and first differences in -2..2.

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`%I #10 Mar 20 2017 09:51:06
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`%S 1,2,2,6,11,33,86,278,873,2938,9904,34321,119673,422725,1502590,
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`%T 5381671,19377063,70138385,254978018,930709334,3409356533,12530190100,
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`%U 46188325542,170723964752,632624262841,2349655631568,8745690221340,32617408075856
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`%N Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and first differences in -2..2.
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`%H Andrew Howroyd, <a href="/A209026/b209026.txt">Table of n, a(n) for n = 1..100</a>
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`%e Some solutions for n=6:
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`%e ..0...-1...-1...-2...-2...-2...-1...-1...-2...-1...-1...-1...-2...-1...-1...-1
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`%e ..0....0....0....0....0...-1...-1...-1...-1...-1...-1....0...-1...-1....0....0
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`%e ..0....0....0....1....0....1....0....0....1...-1....1....1....1....0...-1....1
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`%e ..0....1....0....0....1....0....0....0....2....1....0...-1....1....1....0...-1
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`%e ..0...-1....0....1....1....2....1....2....1....1....0....0....1....0....2....1
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`%e ..0....1....1....0....0....0....1....0...-1....1....1....1....0....1....0....0
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`%Y Column 2 of A209032.
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`%K nonn
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`%O 1,2
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`%A _R. H. Hardin_, Mar 04 2012
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`%E a(22)-a(28) from _Andrew Howroyd_, Mar 19 2017
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