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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | -3 |
| 5 | 11 |
| 6 | -5 |
| 7 | -83 |
| 8 | -2919 |
| 9 | 18838 |
| 10 | 118371 |
| 11 | 583826 |
| 12 | -27365327 |
| 13 | -12780260 |
| 14 | 405396069 |
| 15 | 32646641041 |
| 16 | -232690739007 |
| 17 | 4816360930145 |
| 18 | -46984166770283 |
| 19 | -541620811734953 |
| 20 | -49355727191815599 |
| 21 | 907100235094018036 |
| 22 | 10877428540752188625 |
| 23 | 139350853273096742762 |