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.
?(IntegerQ[Sqrt[8 # + 1]] &)], {k, 105}] (* _Jayanta Basu's wiki page.
?(IntegerQ[Sqrt[8 # + 1]] &)], {k, 105}] (* _Jayanta Basu has authored 0 sequences.