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Number of n-bead necklaces labeled with numbers -6..6 allowing reversal, with sum zero and three times sum of squares <= n*(6)*(6+1).
1

%I #12 Mar 12 2017 22:49:51

%S 1,4,17,136,1073,10372,105147,1111859,11969879,132339307,1483656527,

%T 16847824961,193620920219,2242918877972,26215739119341,

%U 308466499187272,3650953780091983,43460429194159752,519724194908777521,6242649556702436466

%N Number of n-bead necklaces labeled with numbers -6..6 allowing reversal, with sum zero and three times sum of squares <= n*(6)*(6+1).

%H Andrew Howroyd, <a href="/A208803/b208803.txt">Table of n, a(n) for n = 1..40</a>

%e Some solutions for n=6:

%e .-6...-3...-5...-4...-5...-5...-4...-4...-3...-5...-5...-5...-5...-6...-5...-3

%e ..1....2...-1....4...-1....1....3...-3...-3....0...-2...-1...-4...-1....3....1

%e ..0...-2....2...-3...-3....2....0....4...-1...-3....3...-2....2....0....0....1

%e ..2....3....0...-1....6...-3...-3...-2....5....3....2....3....1....5...-1...-2

%e ..0...-2....3...-2....0....1...-1....4....2....2....3....6....2....2...-1....0

%e ..3....2....1....6....3....4....5....1....0....3...-1...-1....4....0....4....3

%Y Column 6 of A208805.

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 01 2012

%E a(13)-a(20) from _Andrew Howroyd_, Mar 02 2017