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 | 120 |
| 2 | -6120 |
| 3 | 737760 |
| 4 | -107249640 |
| 5 | 17385063120 |
| 6 | -3014720249760 |
| 7 | 547287510713280 |
| 8 | -102701836021530600 |
| 9 | 19762301660609250840 |
| 10 | -3878226140959368843120 |
| 11 | 773209219953012480001440 |
| 12 | -156173318001506652330786720 |
| 13 | 31888935085481430265623676560 |