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) |
|---|---|
| 2 | 1 |
| 3 | 432 |
| 4 | 39960 |
| 5 | -1418560 |
| 6 | 17312940 |
| 7 | -71928864 |
| 8 | -462815680 |
| 9 | 7500885120 |
| 10 | -38038437810 |
| 11 | 29000909200 |
| 12 | 729783353376 |
| 13 | -4661016429888 |
| 14 | 13691625085880 |
| 15 | -16503845217120 |
| 16 | -14982974507520 |
| 17 | 45085348093056 |
| 18 | 99234456545637 |
| 19 | -157805792764560 |
| 20 | -1644659689877680 |