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 | 1 |
| 3 | 3 |
| 4 | 16 |
| 5 | 75 |
| 6 | 384 |
| 7 | 1805 |
| 8 | 8640 |
| 9 | 42336 |
| 10 | 207368 |
| 11 | 995808 |
| 12 | 5184000 |
| 13 | 24192672 |
| 14 | 121730700 |
| 15 | 594350400 |
| 16 | 2921811200 |