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 | 1 |
| 2 | -11 |
| 3 | -1 |
| 4 | 1243 |
| 5 | -49 |
| 6 | -75613 |
| 7 | 599 |
| 8 | 234671 |
| 9 | -803 |
| 10 | -4955857 |
| 11 | 53443 |
| 12 | 921931911863 |
| 13 | -449291 |
| 14 | -23461249769 |
| 15 | 1237447 |
| 16 | 917870505450709 |
| 17 | -82659252107 |
| 18 | -959539811053709101 |
| 19 | 145633840717 |
| 20 | 20593004175300735901 |
| 21 | -12278015226517 |