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 | 2 |
| 3 | 0 |
| 4 | -96 |
| 5 | 1875 |
| 6 | -32184 |
| 7 | 554631 |
| 8 | -9773056 |
| 9 | 172718325 |
| 10 | -2874200000 |
| 11 | 35973317666 |
| 12 | 218394869760 |
| 13 | -46968959184459 |
| 14 | 2890848443624064 |
| 15 | -147665402789062500 |
| 16 | 7121567693920010240 |
| 17 | -337669517265832692843 |
| 18 | 15985827659730523364352 |
| 19 | -759295252512454596032456 |