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.
+ 7; say $p if is_prime($p); } # _Dana Jacobsen's wiki page.
+ 7; say $p if is_prime($p); } # _Dana Jacobsen has authored 0 sequences.