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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 16 |
| 5 | 60 |
| 6 | 540 |
| 7 | 3024 |
| 8 | 32256 |
| 9 | 241920 |
| 10 | 3024000 |
| 11 | 28512000 |
| 12 | 410572800 |
| 13 | 4670265600 |
| 14 | 76281004800 |
| 15 | 1017080064000 |
| 16 | 18598035456000 |
| 17 | 284549942476800 |
| 18 | 5762136335155200 |
| 19 | 99527809425408000 |
| 20 | 2211729098342400000 |
| 21 | 42575785143091200000 |
| 22 | 1030334000462807040000 |