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 | -3 |
| 4 | -38 |
| 5 | -135 |
| 6 | -4315 |
| 7 | -48125 |
| 8 | -950684 |
| 9 | -7217406 |
| 10 | -682590930 |
| 11 | -6554931075 |
| 12 | -903921420138 |
| 13 | -10496162430897 |
| 14 | -132415122967127 |
| 15 | -3606726811032345 |
| 16 | -896549281211592008 |
| 17 | -14008671728814262500 |
| 18 | -4425739007479443851340 |