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 A093029 #15 Aug 17 2021 06:32:46 %S A093029 5,10,29,34,48,53,67,72,86,91,109,114,128,133,147,152,166,171,185,190, %T A093029 208,213,227,232,246,251,265,270,289,294,307,312,326,331,345,350,369, %U A093029 374,388,393,406,411,425,430,449,454,468,473,487,492,500,519,524,538 %N A093029 Indices of terms in A093019 with value 9. %C A093029 Integers which require a following 9 to have a valid Luhn mod 10 check digit. %H A093029 Reinhard Zumkeller, <a href="/A093029/b093029.txt">Table of n, a(n) for n = 1..10000</a> %H A093029 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 A093029 Webopedia, <a href="http://www.webopedia.com/TERM/L/Luhn_formula.html">Luhn formula</a> %H A093029 Wikipedia, <a href="http://en.wikipedia.org/wiki/Luhn_algorithm">Luhn algorithm</a> %H A093029 <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a> %F A093029 A093019(a(n)) = 9. - _Reinhard Zumkeller_, Nov 08 2014 %e A093029 10 is in the sequence because A093019(10)=9; 109 has a valid Luhn mod 10 check digit. %o A093029 (Haskell) %o A093029 a093029 n = a093029_list !! (n-1) %o A093029 a093029_list = filter ((== 9) . a093019) [0..] %o A093029 -- _Reinhard Zumkeller_, Nov 08 2014 %Y A093029 Cf. A093017-A093028. %K A093029 easy,nonn,base %O A093029 1,1 %A A093029 _Ray Chandler_, Apr 03 2004 %E A093029 Offset changed by _Reinhard Zumkeller_, Nov 08 2014