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 A006031 #5 Jun 29 2017 15:33:01 %S A006031 3,7,137,283,883,991,1021,1193,3671 %N A006031 Erroneous version of A016054. %H A006031 H. Dubner, <a href="/A028491/a028491.pdf">Generalized repunit primes</a>, Math. Comp., 61 (1993), 927-930. [Annotated scanned copy] %K A006031 dead %O A006031 1,1