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 | 1 |
| 5 | -7 |
| 6 | -47 |
| 7 | -55 |
| 8 | 449 |
| 9 | 2897 |
| 10 | 18209 |
| 11 | 5105 |
| 12 | -1441087 |
| 13 | -7252983 |
| 14 | 41192817 |
| 15 | 341550201 |
| 16 | 2660018305 |
| 17 | 43255573537 |
| 18 | -460752070079 |
| 19 | -11238852308639 |
| 20 | 21450325749889 |
| 21 | 963068748879257 |
| 22 | 1057483104728337 |
| 23 | 153386988236833449 |