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) |
|---|---|
| 4 | 1 |
| 5 | -5 |
| 6 | 55 |
| 7 | -350 |
| 8 | 3969 |
| 9 | -31563 |
| 10 | 408050 |
| 11 | -3920950 |
| 12 | 58206676 |
| 13 | -657328100 |
| 14 | 11111159696 |
| 15 | -144321864960 |
| 16 | 2747845864464 |
| 17 | -40364369180016 |
| 18 | 856755330487200 |
| 19 | -14042902728462624 |
| 20 | 329258021171239296 |
| 21 | -5956512800554963584 |
| 22 | 153050034289602269952 |
| 23 | -3028534064042216488704 |
| 24 | 84691080748928315003904 |