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 A124299 #11 Jan 15 2025 12:15:27 %S A124299 17,167,1669,16673,166723,1667227,16672267,166722667,1667226667, %T A124299 16672266659,166722666527,1667226665213,16672266652081, %U A124299 166722666520801,1667226665207989,16672266652079879,166722666520798747,1667226665207987467,16672266652079874607,166722666520798746053 %N A124299 Largest prime < 10*a(n-1), a(1)=17. %H A124299 Harvey P. Dale, <a href="/A124299/b124299.txt">Table of n, a(n) for n = 1..300</a> %t A124299 NestList[NextPrime[10#,-1]&,17,20] (* _Harvey P. Dale_, Sep 05 2013 *) %Y A124299 Cf. A124262. %K A124299 nonn %O A124299 1,1 %A A124299 _Artur Jasinski_, Dec 16 2006