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 A093020 #15 Aug 17 2021 06:27:02 %S A093020 0,19,24,38,43,57,62,76,81,95,104,118,123,137,142,156,161,175,180,199, %T A093020 203,217,222,236,241,255,260,279,284,298,302,316,321,335,340,359,364, %U A093020 378,383,397,401,415,420,439,444,458,463,477,482,496,509,514,528,533 %N A093020 Indices of terms in A093019 with value 0. %C A093020 Integers which require a following 0 to have a valid Luhn mod 10 check digit. %H A093020 Reinhard Zumkeller, <a href="/A093020/b093020.txt">Table of n, a(n) for n = 1..10000</a> %H A093020 John Kilgo, <a href="https://web.archive.org/web/20040627030859/http://www.dotnetjohn.com/articles/articleid97.aspx">Using the Luhn Algorithm</a>, DotNetJohn.com. %H A093020 Webopedia, <a href="http://www.webopedia.com/TERM/L/Luhn_formula.html">Luhn formula</a> %H A093020 Wikipedia, <a href="http://en.wikipedia.org/wiki/Luhn_algorithm">Luhn algorithm</a> %H A093020 <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a> %F A093020 A093019(a(n)) = 0. - _Reinhard Zumkeller_, Nov 08 2014 %e A093020 19 is in the sequence because A093019(19)=0; 190 has a valid Luhn mod 10 check digit. %o A093020 (Haskell) %o A093020 a093020 n = a093020_list !! (n-1) %o A093020 a093020_list = filter ((== 0) . a093019) [0..] %o A093020 -- _Reinhard Zumkeller_, Nov 08 2014 %Y A093020 Cf. A093017-A093029. %K A093020 easy,nonn,base %O A093020 1,2 %A A093020 _Ray Chandler_, Apr 03 2004 %E A093020 Offset changed by _Reinhard Zumkeller_, Nov 08 2014