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 | 0 |
| 2 | 4 |
| 3 | 5 |
| 4 | 120 |
| 5 | 125 |
| 6 | 12201 |
| 7 | 70800 |
| 8 | 74657 |
| 9 | 29526432 |
| 10 | 37132574 |
| 11 | 89210424 |
| 12 | 124777688 |
| 13 | 120392102955 |
| 14 | 48617257062792 |
| 15 | 343289046464505 |
| 16 | 7519663359716376 |
| 17 | 1214022599940709056 |
| 18 | 40644839476190305216 |
| 19 | 87437200646372849005 |
| 20 | 98628693371623948080 |
| 21 | 375871306587181970568 |