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 A328741 #11 Nov 03 2019 16:03:55 %S A328741 0,0,0,0,2,9,50,206,862,3384,13250,50852,194810,741884,2823712, %T A328741 10735998,40843370,155483873,592614050,2261585918,8643288808, %U A328741 33080772468,126797503250,486710415710,1870851589552,7201012694120,27752927349880,107092389688830,413729680838330 %N A328741 Number of n-bead necklace structures which are not self-equivalent under a nonzero rotation using exactly four different colored beads. %C A328741 Permuting the colors does not change the structure. %H A328741 Andrew Howroyd, <a href="/A328741/b328741.txt">Table of n, a(n) for n = 1..200</a> %F A328741 a(p) = A056297(p) = A056305(p) for prime p. %e A328741 For n=6, the 9 necklace structures are: aaabcd, aabacd, aabcad, aabbcd, aabcbd, aabcdb, aacbdb, ababcd, abacbd. %Y A328741 Column 4 of A327693. %Y A328741 Cf. A056297, A056305, A328740, A328743. %K A328741 nonn %O A328741 1,5 %A A328741 _Andrew Howroyd_, Oct 26 2019