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 | -99 |
| 3 | -9601 |
| 4 | -891099 |
| 5 | -74657401 |
| 6 | -4598985699 |
| 7 | 83304101999 |
| 8 | 105616323905301 |
| 9 | 26458809087970199 |
| 10 | 4788219040686298701 |
| 11 | 620396956870561833599 |
| 12 | 15434896384804497301701 |
| 13 | -25743663357271554846442201 |