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.
?(DigitCount[#, 2, 1] == 3 &)]; Array[a, 100] (* _Amiram Eldar's wiki page.
?(DigitCount[#, 2, 1] == 3 &)]; Array[a, 100] (* _Amiram Eldar has authored 0 sequences.