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 A104091 #3 Oct 01 2013 17:58:09 %S A104091 5,31,211,1291,7759,46649,279919,1679609,10077689,60466169,362796997, %T A104091 2176782317,13060693999,78364164083,470184984569,2821109907437, %U A104091 16926659444687,101559956668403,609359740010477,3656158440062969 %N A104091 Largest prime <= 6^n. %o A104091 (PARI) g(n,b) = for(x=0,n,print1(precprime(b^x)",")) %K A104091 easy,nonn %O A104091 1,1 %A A104091 _Cino Hilliard_, Mar 03 2005