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 | -14 |
| 5 | 86 |
| 6 | -650 |
| 7 | 5822 |
| 8 | -60287 |
| 9 | 708873 |
| 10 | -9334633 |
| 11 | 136142011 |
| 12 | -2179136696 |
| 13 | 37987580268 |
| 14 | -716513806824 |
| 15 | 14540745561432 |
| 16 | -315936103907094 |
| 17 | 7318039354370826 |
| 18 | -180020739049731594 |
| 19 | 4687207255550122014 |
| 20 | -128782014195949550724 |
| 21 | 3723598212075752653284 |
| 22 | -113023054997369519314572 |