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 | 3 |
| 3 | 21 |
| 4 | 300 |
| 5 | 7260 |
| 6 | 259560 |
| 7 | 12703320 |
| 8 | 812871360 |
| 9 | 65841128640 |
| 10 | 6584096534400 |
| 11 | 796675481078400 |
| 12 | 114721266640780800 |
| 13 | 19387894024929830400 |
| 14 | 3800027228319587865600 |
| 15 | 855006126362753549184000 |
| 16 | 218881568348707987666944000 |
| 17 | 63256773252773762936322048000 |