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 | 2 |
| 4 | 4 |
| 5 | 4 |
| 6 | -5 |
| 7 | -23 |
| 8 | 9 |
| 9 | 308 |
| 10 | 1020 |
| 11 | -448 |
| 12 | -19647 |
| 13 | -89379 |
| 14 | -48935 |
| 15 | 1958306 |
| 16 | 13904216 |
| 17 | 34488844 |
| 18 | -223401589 |
| 19 | -3022248531 |
| 20 | -15637955831 |
| 21 | -1081374732 |
| 22 | 738978239768 |
| 23 | 7071581029520 |
| 24 | 29227771327153 |
| 25 | -117008648911367 |