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 | 2 |
| 2 | 23 |
| 3 | 87178286161 |
| 4 | 403291461126605629356979201 |
| 5 | 5502622159812088949850305428800254867109635014075023360001 |