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 A258209 #14 Dec 20 2021 02:37:30
%S A258209 0,1,2,3,4,6,7,8,12,14,15,16,24,26,28,30,31,32,48,52,56,58,60,62,63,
%T A258209 64,96,100,104,106,112,118,120,122,124,126,127,128,192,200,208,212,
%U A258209 224,228,234,236,240,246,248,250,252,254,255,256,384,392,400,416,420,424,426,448,460,466,472,474,480,484,490,494,496,502,504,506,508,510,511,512
%N A258209 Numbers k for which A256999(A059893(k)) = k.
%C A258209 Indexing starts from zero, because a(0) = 0 is a special case.
%C A258209 These numbers correspond to the maximal (lexicographically largest) representatives selected from each equivalence class of those binary necklaces that stay the same (in the same equivalence class) when flipped over (which thus have a bilateral symmetry, please see the examples). A029744(n) gives the number of terms with n significant bits in their binary representation.
%H A258209 Antti Karttunen, <a href="/A258209/b258209.txt">Table of n, a(n) for n = 0..5117</a>
%e A258209 28 ("11100" in binary) is in sequence, because after removing the most significant bit, the binary string "1100" when reversed, "0011", can then be rotated (two steps in either direction) to give "1100" again and "1100" is the lexicographically largest of these rotations.
%e A258209 114 ("1110010" in binary) is NOT in the sequence, because after removing the most significant bit, the binary string "110010" when reversed, "010011", does not yield "110010" no matter how many steps it is rotated (even though it is the lexicographically largest rotation of its class). Thus although 114 is in A257250 (a supersequence of this sequence), it is not included here.
%o A258209 (define (isA258209? n) (= n (A256999 (A059893 n))))
%o A258209 (define A258209 (MATCHING-POS 0 0 isA258209?))
%Y A258209 Cf. A029744, A059893, A256999.
%Y A258209 Subsequence of A257250.
%Y A258209 Differs from A257250 for the first time at n=31, where a(31) = 118, while A257250(31) = 114.
%K A258209 nonn,base
%O A258209 0,3
%A A258209 _Antti Karttunen_, May 31 2015