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 | 2 |
| 3 | 1 |
| 4 | 0 |
| 5 | -1 |
| 6 | -4 |
| 7 | -19 |
| 8 | -110 |
| 9 | -751 |
| 10 | -5898 |
| 11 | -52331 |
| 12 | -517412 |
| 13 | -5639201 |
| 14 | -67153000 |
| 15 | -867349799 |
| 16 | -12075744186 |
| 17 | -180268812991 |
| 18 | -2872225263670 |
| 19 | -48647560669399 |
| 20 | -872783866785512 |
| 21 | -16534245908255329 |
| 22 | -329812134298321068 |
| 23 | -6909520574356487099 |
| 24 | -151679640501544395110 |