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 A066227 #5 Mar 31 2012 10:32:39 %S A066227 2,3,19,157,2917 %N A066227 Number of digits in Mersenne primes with a prime number of digits. %e A066227 a(4) is M21, the 21st Mersenne prime with prime digit count of 2917 %Y A066227 Cf. A028335. %K A066227 nonn,base %O A066227 1,1 %A A066227 _Enoch Haga_, Dec 18 2001