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 A053648 #10 Jan 04 2022 18:53:11 %S A053648 3,7,31,2,127,19,191,8191,13,71,107,131,131071,5,524287,47,83,647, %T A053648 2147483647,23,43,5843,13693,4300921,5843009,584300921,2305843009, %U A053648 5843009213,30584300921,43009213693,2305843009213693951,11,37,61,89,97,137,211,269,449,2111 %N A053648 Scan decimal expansion of Mersenne primes (A000668), recording all primes seen. %e A053648 19 and 191 are found in the Mersenne prime 8191. %Y A053648 Cf. A000668. %K A053648 nonn,base,less %O A053648 1,1 %A A053648 _Enoch Haga_, Feb 19 2000 %E A053648 Missing a(27) inserted and more terms from _Sean A. Irvine_, Jan 04 2022