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 | -2 |
| 3 | 19 |
| 4 | -14 |
| 5 | 199 |
| 6 | -137 |
| 7 | 851 |
| 8 | -548 |
| 9 | 4121 |
| 10 | -2533 |
| 11 | 67451 |
| 12 | -40078 |
| 13 | 404869 |
| 14 | -234967 |
| 15 | 1655047 |
| 16 | -940136 |
| 17 | 32428087 |
| 18 | -18383711 |
| 19 | 439693871 |
| 20 | -235204778 |
| 21 | -724823111 |
| 22 | 352226881 |
| 23 | 260572074487 |
| 24 | -130542594044 |
| 25 | -6002444699183 |
| 26 | 3000757572779 |