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 A333943 #4 Apr 15 2020 09:52:57 %S A333943 1,2,3,4,5,7,8,9,10,11,15,16,17,18,19,21,23,31,32,33,34,35,36,37,39, %T A333943 41,42,43,45,47,63,64,65,66,67,68,69,71,73,74,75,77,79,81,83,85,87,91, %U A333943 95,127,128,129,130,131,132,133,135,136,137,138,139,141,143 %N A333943 Numbers k such that the k-th composition in standard order is a reversed necklace. %C A333943 A necklace is a finite sequence that is lexicographically minimal among all of its cyclic rotations. Reversed necklaces are different from co-necklaces (A333764). %C A333943 A composition of n is a finite sequence of positive integers summing to n. The k-th composition in standard order (row k of A066099) is obtained by taking the set of positions of 1's in the reversed binary expansion of k, prepending 0, taking first differences, and reversing again. This gives a bijective correspondence between nonnegative integers and integer compositions. %e A333943 The sequence together with the corresponding reversed necklaces begins: %e A333943 1: (1) 32: (6) 69: (4,2,1) %e A333943 2: (2) 33: (5,1) 71: (4,1,1,1) %e A333943 3: (1,1) 34: (4,2) 73: (3,3,1) %e A333943 4: (3) 35: (4,1,1) 74: (3,2,2) %e A333943 5: (2,1) 36: (3,3) 75: (3,2,1,1) %e A333943 7: (1,1,1) 37: (3,2,1) 77: (3,1,2,1) %e A333943 8: (4) 39: (3,1,1,1) 79: (3,1,1,1,1) %e A333943 9: (3,1) 41: (2,3,1) 81: (2,4,1) %e A333943 10: (2,2) 42: (2,2,2) 83: (2,3,1,1) %e A333943 11: (2,1,1) 43: (2,2,1,1) 85: (2,2,2,1) %e A333943 15: (1,1,1,1) 45: (2,1,2,1) 87: (2,2,1,1,1) %e A333943 16: (5) 47: (2,1,1,1,1) 91: (2,1,2,1,1) %e A333943 17: (4,1) 63: (1,1,1,1,1,1) 95: (2,1,1,1,1,1) %e A333943 18: (3,2) 64: (7) 127: (1,1,1,1,1,1,1) %e A333943 19: (3,1,1) 65: (6,1) 128: (8) %e A333943 21: (2,2,1) 66: (5,2) 129: (7,1) %e A333943 23: (2,1,1,1) 67: (5,1,1) 130: (6,2) %e A333943 31: (1,1,1,1,1) 68: (4,3) 131: (6,1,1) %t A333943 stc[n_]:=Differences[Prepend[Join@@Position[Reverse[IntegerDigits[n,2]],1],0]]//Reverse; %t A333943 neckQ[q_]:=Array[OrderedQ[{q,RotateRight[q,#1]}]&,Length[q]-1,1,And]; %t A333943 Select[Range[100],neckQ[Reverse[stc[#]]]&] %Y A333943 The non-reversed version is A065609. %Y A333943 The dual version is A328595. %Y A333943 Binary necklaces are A000031. %Y A333943 Necklace compositions are A008965. %Y A333943 Necklaces covering an initial interval are A019536. %Y A333943 Numbers whose prime signature is a necklace are A329138. %Y A333943 Length of co-Lyndon factorization of binary expansion is A329312. %Y A333943 Length of Lyndon factorization of reversed binary expansion is A329313. %Y A333943 All of the following pertain to compositions in standard order (A066099): %Y A333943 - Length is A000120. %Y A333943 - Sum is A070939. %Y A333943 - Runs are counted by A124767. %Y A333943 - Rotational symmetries are counted by A138904. %Y A333943 - Strict compositions are A233564. %Y A333943 - Constant compositions are A272919. %Y A333943 - Lyndon compositions are A275692. %Y A333943 - Co-Lyndon compositions are A326774. %Y A333943 - Aperiodic compositions are A328594. %Y A333943 - Length of Lyndon factorization is A329312. %Y A333943 - Rotational period is A333632. %Y A333943 - Co-necklaces are A333764. %Y A333943 - Length of co-Lyndon factorization is A334029. %Y A333943 Cf. A000740, A001037, A027375, A059966, A211100, A302291, A328596, A329142, A333765, A333939, A333941. %K A333943 nonn %O A333943 1,2 %A A333943 _Gus Wiseman_, Apr 14 2020