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 A179866 #11 May 01 2013 21:02:11
%S A179866 2,1531,16651,15514861
%N A179866 A057330 with duplicates omitted.
%e A179866 2*2-1=3,2*3-1=5,2*5-1=11;
%e A179866 2,3,5;
%e A179866 1531,3061,6121,12241,24481;
%e A179866 16651,33301,66601,133201,266401,532801,1065601;
%e A179866 15514861,31029721,62059441,124118881,248237761,496475521,992951041,1985902081;
%t A179866 q=1; Reap[Do[lst={a=Prime[n]}; While[PrimeQ[a=2a-1], AppendTo[lst,a]]; If[Length[lst]>q, q=Length[lst]; Print[lst]; Sow[lst[[1]]]], {n,10^6}]][[2,1]]
%Y A179866 Cf. A057330, A005382
%K A179866 nonn,more
%O A179866 1,1
%A A179866 _Vladimir Joseph Stephan Orlovsky_, Jan 11 2011
%E A179866 Edited by _N. J. A. Sloane_, Jan 11 2011.