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 | 0 |
| 3 | 3 |
| 4 | 24 |
| 5 | 180 |
| 6 | 1440 |
| 7 | 12600 |
| 8 | 120960 |
| 9 | 1270080 |
| 10 | 14515200 |
| 11 | 179625600 |
| 12 | 2395008000 |
| 13 | 34248614400 |
| 14 | 523069747200 |
| 15 | 8499883392000 |
| 16 | 146459529216000 |
| 17 | 2667655710720000 |
| 18 | 51218989645824000 |
| 19 | 1033983353475072000 |
| 20 | 21896118073589760000 |
| 21 | 485363950631239680000 |
| 22 | 11240007277776076800000 |