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 | 0 |
| 2 | 12 |
| 3 | 48 |
| 4 | 540 |
| 5 | 4320 |
| 6 | 42240 |
| 7 | 403200 |
| 8 | 4038300 |
| 9 | 40958400 |
| 10 | 423550512 |
| 11 | 4434978240 |
| 12 | 46982827584 |
| 13 | 502437551616 |
| 14 | 5417597053440 |
| 15 | 58831951546368 |
| 16 | 642874989479580 |
| 17 | 7063600894137216 |
| 18 | 77991775777488144 |
| 19 | 864910651813116480 |