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 | 18 |
| 4 | 192 |
| 5 | 2520 |
| 6 | 39600 |
| 7 | 725760 |
| 8 | 15200640 |
| 9 | 358162560 |
| 10 | 9376819200 |
| 11 | 270037152000 |
| 12 | 8483597337600 |
| 13 | 288734500454400 |
| 14 | 10582834303641600 |
| 15 | 415593298568448000 |
| 16 | 17408598098411520000 |
| 17 | 774797125808369664000 |