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 | 4 |
| 3 | 10 |
| 4 | 48 |
| 5 | 216 |
| 6 | 1440 |
| 7 | 9360 |
| 8 | 80640 |
| 9 | 685440 |
| 10 | 7257600 |
| 11 | 76204800 |
| 12 | 958003200 |
| 13 | 11975040000 |
| 14 | 174356582400 |
| 15 | 2528170444800 |
| 16 | 41845579776000 |
| 17 | 690452066304000 |
| 18 | 12804747411456000 |
| 19 | 236887827111936000 |
| 20 | 4865804016353280000 |
| 21 | 99748982335242240000 |
| 22 | 2248001455555215360000 |