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 | 4 |
| 2 | 20 |
| 3 | 120 |
| 4 | 816 |
| 5 | 5984 |
| 6 | 45760 |
| 7 | 357760 |
| 8 | 2829056 |
| 9 | 22500864 |
| 10 | 179481600 |
| 11 | 1433753600 |
| 12 | 11461636096 |
| 13 | 91659526144 |
| 14 | 733141975040 |
| 15 | 5864598896640 |
| 16 | 46914643623936 |
| 17 | 375308558925824 |
| 18 | 3002434111406080 |
| 19 | 24019335451770880 |
| 20 | 192154133857304576 |
| 21 | 1537230871833083904 |
| 22 | 12297838178567454720 |