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.
?(Not@*PrimePowerQ)] & @@ # &, Partition[Prime@ Range[120], 2, 1]] (* _Michael De Vlieger has authored 0 sequences.