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 | 1 |
| 3 | 1 |
| 4 | -5 |
| 5 | -29 |
| 6 | -89 |
| 7 | -209 |
| 8 | -9239 |
| 9 | -120455 |
| 10 | -801359 |
| 11 | -3674879 |
| 12 | 15450931 |
| 13 | 505760971 |
| 14 | 4925214295 |
| 15 | 30957618511 |
| 16 | -3280733667119 |
| 17 | -49063880680079 |
| 18 | -327527326905119 |
| 19 | -1087577476736255 |
| 20 | 97366167074820331 |
| 21 | 1723137650565888691 |
| 22 | 13360549076712501511 |