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 A328038 #12 Oct 25 2019 16:34:12 %S A328038 0,0,1,1,4,8,25,62,176,470,1311,3620,10094,28209,79236,223270,631240, %T A328038 1790213,5090995,14515788,41484907,118821599,341008317,980487770, %U A328038 2823961866,8146372122,23534556225,68083326558,197209108054,571910949743,1660395053569,4825540091342 %N A328038 Number of primitive (period n) n-bead bracelet structures which are not periodic palindromes using exactly three different colored beads. %C A328038 Permuting the colors of the beads will not change the structure. %H A328038 Andrew Howroyd, <a href="/A328038/b328038.txt">Table of n, a(n) for n = 1..200</a> %F A328038 a(n) = A056367(n) - A056519(n). %e A328038 For n = 3, the 1 bracelet structure has the pattern: ABC. %e A328038 For n = 4, the 1 bracelet structure has the pattern: AABC. %e A328038 For n = 5, the 4 bracelet structures have the patterns: AAABC, AABAC, AABBC, ABABC. The pattern ABBAC is excluded because it is a periodic palindrome. %e A328038 For n = 6, the 8 bracelet structures have the patterns: ABCCCC, ABBCCC, ABBBCB, ABBCBC, ABBCCB, ABCBBC, AABBCC, AABCBC. %Y A328038 Column 3 of A309784. %Y A328038 Cf. A056367, A056519, A328035, A328039, A328657. %K A328038 nonn %O A328038 1,5 %A A328038 _Andrew Howroyd_, Oct 02 2019