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 | 3 |
| 2 | -21 |
| 3 | -139 |
| 4 | 531 |
| 5 | 6489 |
| 6 | -9723 |
| 7 | -292293 |
| 8 | -135117 |
| 9 | 12514313 |
| 10 | 29905809 |
| 11 | -501239553 |
| 12 | -2310673379 |
| 13 | 18245192679 |
| 14 | 140574917259 |
| 15 | -562805403867 |
| 16 | -7557237645741 |
| 17 | 11275709877369 |
| 18 | 371974318253601 |
| 19 | 201852054629631 |
| 20 | -16932135947326551 |
| 21 | -42530838930147813 |
| 22 | 709138646702505999 |