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 | -11 |
| 5 | 43 |
| 6 | -83 |
| 7 | -275 |
| 8 | 3833 |
| 9 | -21561 |
| 10 | 51369 |
| 11 | 375593 |
| 12 | -5860147 |
| 13 | 40452371 |
| 14 | -101676235 |
| 15 | -1409619211 |
| 16 | 23912208945 |
| 17 | -189650997937 |
| 18 | 454996127889 |
| 19 | 11250036170129 |
| 20 | -204691511497499 |
| 21 | 1799897065507003 |
| 22 | -3741969787709699 |
| 23 | -164548323889940675 |
| 24 | 3183842522596250537 |
| 25 | -30356999697044585833 |