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 | -2 |
| 4 | -5 |
| 5 | -7 |
| 6 | -37 |
| 7 | -17 |
| 8 | 887 |
| 9 | 1405 |
| 10 | 168919 |
| 11 | 958271 |
| 12 | 3086837 |
| 13 | 122693929 |
| 14 | 559876951 |
| 15 | 15779421743 |
| 16 | 337767590383 |
| 17 | 1531923385313 |
| 18 | 11912361112367 |
| 19 | -6819537030283 |
| 20 | -21032925955607701 |
| 21 | -313699426574980519 |
| 22 | -16703816669710968821 |
| 23 | -212752402370938916881 |