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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | -18 |
| 4 | -190 |
| 5 | 1035 |
| 6 | 25305 |
| 7 | -120260 |
| 8 | -5954940 |
| 9 | 22115925 |
| 10 | 2197084175 |
| 11 | -5141457750 |
| 12 | -1173207584250 |
| 13 | 769657081375 |
| 14 | 856957094209125 |
| 15 | 1127788828491000 |
| 16 | -821262134429035000 |
| 17 | -2922085673288364375 |
| 18 | 1000078365473764126875 |
| 19 | 6056214264965246443750 |
| 20 | -1508740652939902034493750 |