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 | 0 |
| 3 | -27 |
| 4 | -256 |
| 5 | 1875 |
| 6 | 0 |
| 7 | 252105 |
| 8 | 4718592 |
| 9 | -55801305 |
| 10 | 0 |
| 11 | -18415376595 |
| 12 | -515978035200 |
| 13 | 8479520844795 |
| 14 | 0 |
| 15 | 5195043369140625 |
| 16 | 193953851139686400 |
| 17 | -4086470036057634225 |
| 18 | 0 |
| 19 | -4014187339733760264075 |
| 20 | -187280916480000000000000 |
| 21 | 4816074142389727429287075 |
| 22 | 0 |