cp's OEIS Frontend

A209487 Number of 6-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.

%I A209487 #16 Mar 19 2021 09:52:51
%S A209487 11,136,731,2606,7179,16660,34233,64220,112263,185506,292759,444680,
%T A209487 653957,935472,1306483,1786806,2398979,3168444,4123729,5296612,
%U A209487 6722303,8439626,10491183,12923536,15787389,19137752,23034123,27540670,32726395
%N A209487 Number of 6-bead necklaces labeled with numbers -n..n allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.
%C A209487 Row 6 of A209485.
%H A209487 R. H. Hardin, <a href="/A209487/b209487.txt">Table of n, a(n) for n = 1..210</a>
%F A209487 Empirical: a(n) = 5*a(n-1) - 10*a(n-2) + 11*a(n-3) - 10*a(n-4) + 11*a(n-5) - 10*a(n-6) + 5*a(n-7) - a(n-8) for n > 9.
%e A209487 Some solutions for n=8:
%e A209487   -6  -8  -6  -7  -8  -7  -7  -8  -8  -4  -5  -6  -8  -8  -6  -8
%e A209487   -1  -3  -6  -6  -2   0  -5   0  -4  -3   3  -2   1  -2  -3   3
%e A209487    2  -1   0   6   6   6   2  -2  -5   6  -2   3  -4   7  -4  -4
%e A209487   -2  -1  -3   2  -1  -7   5  -3   8  -3  -4   6  -3  -4   4   6
%e A209487    6   6   7   4   6   6   6   5   8  -4   2  -3   8   4   1  -1
%e A209487    1   7   8   1  -1   2  -1   8   1   8   6   2   6   3   8   4
%K A209487 nonn
%O A209487 1,1
%A A209487 _R. H. Hardin_, Mar 09 2012