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 | -1 |
| 3 | -1 |
| 4 | 41 |
| 5 | -375 |
| 6 | -3001 |
| 7 | 177063 |
| 8 | -990543 |
| 9 | -144800527 |
| 10 | 3644593711 |
| 11 | 214013895023 |
| 12 | -12488200175463 |
| 13 | -553322483517383 |
| 14 | 61495192102867639 |
| 15 | 2469939623420627543 |
| 16 | -448608666325921194271 |
| 17 | -19104207797417792353951 |
| 18 | 4742067751530355028847327 |