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 A194181 #35 Jun 15 2023 02:27:47
%S A194181 3,1,7,1,7,6,5,4,7,3,4,1,5,9,0,4,9,5,7,2,2,8,7,0,9,7,0,8,7,5,0,6,1,1,
%T A194181 6,5,6,7,9,7,0,5,0,7,0,8,3,9,6,2,8,5,7,2,4,1,6,4,1,8,6,8,9,8,4,3,7,1,
%U A194181 3,7,6,8,8,5,8,5,6,1,9,2,6,6,8,8,5,2,3,1,0,8,0,7,4,7,1,5,6,0,4,5,4
%N A194181 Decimal expansion of the (finite) value of Sum_{k >= 1, k has no even digit in base 10 } 1/k.
%C A194181 For an elementary proof that this series is convergent, see Honsberger's reference. - _Bernard Schott_, Jan 13 2022
%D A194181 Ross Honsberger, Mathematical Gems II, Dolciani Mathematical Expositions No. 2, Mathematical Association of America, 1976, pp. 102 and 177.
%H A194181 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 A194181 Thomas Schmelzer and Robert Baillie, <a href="http://www.jstor.org/stable/27642532">Summing a curious, slowly convergent, harmonic subseries</a>, American Mathematical Monthly 115:6 (2008), pp. 525-540; <a href="http://eprints.maths.ox.ac.uk/1106/1/NA-06-17.pdf">preprint</a>.
%H A194181 Wikipedia, <a href="http://en.wikipedia.org/wiki/Kempner_series">Kempner series</a>.
%F A194181 Equals Sum_{n>=1} 1/A014261(n). - _Bernard Schott_, Jan 13 2022
%e A194181 3.17176547341590495722870970875061165679705070839628572416418689843...
%t A194181 RealDigits[kSum[{0, 2, 4, 6, 8}, 120 ]][[1]] (* _Amiram Eldar_, Jun 15 2023, using Baillie and Schmelzer's kempnerSums.nb, see Links *)
%Y A194181 Cf. A014261, A082830, A194182.
%K A194181 cons,nonn
%O A194181 1,1
%A A194181 _Robert G. Wilson v_, Aug 18 2011