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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 96 |
| 6 | 576 |
| 7 | 3312 |
| 8 | 21456 |
| 9 | 152784 |
| 10 | 1237536 |
| 11 | 9984096 |
| 12 | 133494912 |
| 13 | 1412107776 |
| 14 | 16369357824 |
| 15 | 206123325696 |
| 16 | 2866280276736 |
| 17 | 36809077162752 |
| 18 | 592066290710016 |
| 19 | 8800038127378944 |
| 20 | 136876273991755776 |
| 21 | 2197453620220010496 |
| 22 | 37915306084793106432 |