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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 48 |
| 5 | 376 |
| 6 | 3600 |
| 7 | 40592 |
| 8 | 525952 |
| 9 | 7692928 |
| 10 | 125303040 |
| 11 | 2248366592 |
| 12 | 44055035904 |
| 13 | 935800603648 |
| 14 | 21417131939840 |
| 15 | 525346642337792 |
| 16 | 13748654428323840 |
| 17 | 382362034331877376 |
| 18 | 11260657076602208256 |
| 19 | 350082293087247269888 |
| 20 | 11457214800338786713600 |