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 | 8 |
| 4 | 60 |
| 5 | 480 |
| 6 | 4200 |
| 7 | 40320 |
| 8 | 423360 |
| 9 | 4838400 |
| 10 | 59875200 |
| 11 | 798336000 |
| 12 | 11416204800 |
| 13 | 174356582400 |
| 14 | 2833294464000 |
| 15 | 48819843072000 |
| 16 | 889218570240000 |
| 17 | 17072996548608000 |
| 18 | 344661117825024000 |
| 19 | 7298706024529920000 |
| 20 | 161787983543746560000 |