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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | -6 |
| 4 | -2 |
| 5 | 243 |
| 6 | -2031 |
| 7 | 3796 |
| 8 | 187212 |
| 9 | -3860139 |
| 10 | 36467311 |
| 11 | 284357502 |
| 12 | -21796446486 |
| 13 | 538332144295 |
| 14 | -5605176351651 |
| 15 | -182065102478856 |
| 16 | 12963817679287960 |
| 17 | -422751776737348503 |
| 18 | 5483284328996107803 |
| 19 | 327213964461103956802 |
| 20 | -30082452646697648945898 |