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.
?(PrimeQ[#^2 + 1] &)] &, 7] (* _Michael De Vlieger's wiki page.
?(PrimeQ[#^2 + 1] &)] &, 7] (* _Michael De Vlieger has authored 0 sequences.