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Number of n-bead necklaces labeled with numbers -7..7 not allowing reversal, with sum zero and first and second differences in -7..7.
0

%I #6 Mar 13 2017 00:08:30

%S 1,2,7,38,243,1854,14701,116960,916381,7170239,56496359,449785468,

%T 3619072169

%N Number of n-bead necklaces labeled with numbers -7..7 not allowing reversal, with sum zero and first and second differences in -7..7.

%C Column 7 of A209007.

%e Some solutions for n=6:

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

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

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 04 2012