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 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | -8 |
| 5 | 25 |
| 6 | -99 |
| 7 | 721 |
| 8 | -5704 |
| 9 | 40881 |
| 10 | -340325 |
| 11 | 3628801 |
| 12 | -41245511 |
| 13 | 479001601 |
| 14 | -6129725315 |
| 15 | 87212177053 |
| 16 | -1317906346184 |
| 17 | 20922789888001 |
| 18 | -354320889234597 |
| 19 | 6402373705728001 |
| 20 | -121882630320799633 |
| 21 | 2432928081076384321 |
| 22 | -51041048673495232715 |