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 A134722 #2 Mar 30 2012 17:33:50 %S A134722 7,127,131071,2147483647,618970019642690137449562111 %N A134722 Bisection of Mersenne primes A000668. %F A134722 a(n) = A000668(2*n). %e A134722 a(3) = 131071 because the (2*3=6)th Mersenne prime is 131071. %Y A134722 Cf. A000668, A134721. %K A134722 easy,nonn %O A134722 1,1 %A A134722 _Omar E. Pol_, Nov 11 2007