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 | 1 |
| 3 | 1 |
| 4 | -15 |
| 5 | 81 |
| 6 | -159 |
| 7 | -1695 |
| 8 | 19857 |
| 9 | -77775 |
| 10 | -372351 |
| 11 | 6628545 |
| 12 | -24096975 |
| 13 | -232640751 |
| 14 | 2756221601 |
| 15 | 2199811873 |
| 16 | -210934282287 |
| 17 | 553408050417 |
| 18 | 17722961332929 |
| 19 | -95716389015423 |
| 20 | -1950283855292559 |
| 21 | 15527782649242065 |
| 22 | 285278599792984545 |
| 23 | -3006768595808218911 |