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 | -8 |
| 5 | 10 |
| 6 | -372 |
| 7 | -6014 |
| 8 | -194140 |
| 9 | -6851310 |
| 10 | -286013372 |
| 11 | -13629729990 |
| 12 | -731279661488 |
| 13 | -43618952847894 |
| 14 | -2863512195607780 |
| 15 | -205184821861288518 |
| 16 | -15936259396425487780 |
| 17 | -1333664198543385424414 |
| 18 | -119648378626870160202060 |
| 19 | -11456079894214769377662158 |