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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | -3 |
| 5 | 4 |
| 6 | -10 |
| 7 | 636 |
| 8 | -1078 |
| 9 | -18416 |
| 10 | -131976 |
| 11 | 5035920 |
| 12 | 5333592 |
| 13 | 187347744 |
| 14 | -4079616528 |
| 15 | -14669908512 |
| 16 | -140154110640 |
| 17 | 28743506893056 |
| 18 | -92449999037568 |
| 19 | 2738959517576448 |
| 20 | -52969092379214976 |
| 21 | 34211286306178560 |
| 22 | -16812071564735736576 |
| 23 | 1407763084021569335808 |