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.
i) * b^i, A-A' is divisible by b-1 if Sum's wiki page.
i) * b^i, A-A' is divisible by b-1 if Sum has authored 0 sequences.