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 | -1 |
| 5 | -5 |
| 6 | 6 |
| 7 | 57 |
| 8 | -68 |
| 9 | -996 |
| 10 | 1151 |
| 11 | 23487 |
| 12 | -26316 |
| 13 | -703858 |
| 14 | 769268 |
| 15 | 25912425 |
| 16 | -27791388 |
| 17 | -1146924362 |
| 18 | 1212941187 |
| 19 | 60112150656 |
| 20 | -62911402588 |
| 21 | -3686975047595 |
| 22 | 3828485422340 |
| 23 | 262043300715095 |
| 24 | -270475215554448 |
| 25 | -21394371719691000 |