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Number of n-bead necklaces labeled with numbers -2..2 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.
0

%I #6 Mar 13 2017 00:01:33

%S 1,3,6,22,70,265,1007,4055,16593,69429,294509,1265692,5494398,

%T 24065829,106207739,471840078,2108406146,9470071142,42731427358,

%U 193612759011,880517540867

%N Number of n-bead necklaces labeled with numbers -2..2 not allowing reversal, with sum zero and avoiding the pattern z z+1 z+2.

%C Column 2 of A209073.

%e Some solutions for n=6:

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

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

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 04 2012