This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A328658 #8 Nov 03 2019 15:49:26
%S A328658 0,0,1,2,6,19,58,195,651,2294,8122,29607,108276,401389,1494268,
%T A328658 5600204,21065520,79567572,301448098,1145448216,4363328350,
%U A328658 16659757647,63740548126,244337865925,938252884294,3608661283038,13900010654999,53614312021527,207062098878276
%N A328658 Number of primitive (period n) n-bead bracelet structures which are not periodic palindromes using a maximum of four different colored beads.
%C A328658 Permuting the colors of the beads will not change the structure.
%H A328658 Andrew Howroyd, <a href="/A328658/b328658.txt">Table of n, a(n) for n = 1..200</a>
%F A328658 a(n) = Sum_{k=1..4} A309784(n, k).
%F A328658 a(n) = A056363(n) - A056515(n).
%e A328658 For n = 4, the 2 bracelet structures are: AABC, ABCD.
%e A328658 For n = 5, the 6 bracelet structures are: AAABC, AABAC, AABBC, ABABC, AABCD, ABACD.
%Y A328658 Cf. A056363, A056515, A309784, A328039.
%K A328658 nonn
%O A328658 1,4
%A A328658 _Andrew Howroyd_, Oct 24 2019