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 | -3 |
| 5 | -24 |
| 6 | -89 |
| 7 | -244 |
| 8 | 1681 |
| 9 | 24382 |
| 10 | 155401 |
| 11 | 695146 |
| 12 | -7490339 |
| 13 | -157336464 |
| 14 | -1421454033 |
| 15 | -8817579224 |
| 16 | 129268310081 |
| 17 | 3555528110716 |
| 18 | 41578411339441 |
| 19 | 329824291072252 |
| 20 | -6116622750516899 |
| 21 | -207991913454970784 |
| 22 | -2985298421745508329 |