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 A001729 #23 Feb 15 2024 01:52:45
%S A001729 1,2,3,4,5,7,11,12,13,14,15,17,21,22,23,24,25,27,31,32,33,34,35,37,41,
%T A001729 42,43,44,45,47,51,52,53,54,55,57,71,72,73,74,75,77,111,112,113,114,
%U A001729 115,117,121,122,123,124,125,127,131,132,133,134,135,137,141,142
%N A001729 List of numbers whose digits contain no loops (version 1).
%C A001729 The digits 0, 6, 8 and 9 contain loops, but 1, 2, 3, 4 (written in "open" style), 5 and 7 do not.
%H A001729 T. D. Noe, <a href="/A001729/b001729.txt">Table of n, a(n) for n = 1..1000</a>
%H A001729 Robert Baillie and Thomas Schmelzer, <a href="https://library.wolfram.com/infocenter/MathSource/7166/">Summing Kempner's Curious (Slowly-Convergent) Series</a>, Mathematica Notebook kempnerSums.nb, Wolfram Library Archive, 2008.
%H A001729 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%F A001729 Sum_{n>=1} 1/a(n) = 5.427161361994446672956800952211331066904630376796246807177210248900020978222... (calculated using Baillie and Schmelzer's kempnerSums.nb, see Links). - _Amiram Eldar_, Feb 15 2024
%t A001729 Select[Range[150], Intersection[{0, 6, 8, 9}, Union[IntegerDigits[#]]] == {} &] (* _T. D. Noe_, Aug 10 2012 *)
%t A001729 FromDigits/@Flatten[Table[Tuples[{1,2,3,4,5,7},n],{n,3}],1] (* _Harvey P. Dale_, Feb 01 2017 *)
%Y A001729 Cf. A001742 (version 2).
%K A001729 base,nonn,easy
%O A001729 1,2
%A A001729 _N. J. A. Sloane_
%E A001729 Missing 42 and 44 added by _T. D. Noe_, Aug 10 2012