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Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero and first differences in -3..3.
1

%I #11 Mar 20 2017 09:51:08

%S 1,2,4,12,34,144,576,2613,11841,55773,265095,1280476,6238246,30674021,

%T 151874427,756842052,3792315084,19096602857,96586072494,490453174481,

%U 2499410534082,12778951549191,65530990963959,336965088080673,1737060054201011,8975377470866966

%N Number of n-bead necklaces labeled with numbers -3..3 allowing reversal, with sum zero and first differences in -3..3.

%H Andrew Howroyd, <a href="/A209027/b209027.txt">Table of n, a(n) for n = 1..100</a>

%e Some solutions for n=6:

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

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

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

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

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

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

%Y Column 3 of A209032.

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 04 2012

%E a(19)-a(26) from _Andrew Howroyd_, Mar 19 2017