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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 129 |
| 4 | 1587 |
| 5 | 39443 |
| 6 | 1125383 |
| 7 | 30211457 |
| 8 | 1107074979 |
| 9 | 36214609683 |
| 10 | 1433494688871 |
| 11 | 54495716261011 |
| 12 | 2275005440977063 |
| 13 | 95146470595975399 |
| 14 | 4170974287982618639 |
| 15 | 185640304224109725569 |
| 16 | 8492643748223480148419 |
| 17 | 395051289603660979274339 |
| 18 | 18726850582009755291702599 |