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 | 4 |
| 3 | 24 |
| 4 | 168 |
| 5 | 1680 |
| 6 | 18720 |
| 7 | 252000 |
| 8 | 3830400 |
| 9 | 65681280 |
| 10 | 1251936000 |
| 11 | 26225337600 |
| 12 | 599710003200 |
| 13 | 14851444608000 |
| 14 | 396138155212800 |
| 15 | 11320537003776000 |
| 16 | 345079573622784000 |
| 17 | 11176410365632512000 |