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.
| n | a(n) |
|---|---|
| 1 | 990 |
| 2 | 2090209222020090 |
| 3 | 92209290022092090 |
| 4 | 200290202090990220 |
| 5 | 222020200990922029290 |