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 | 1 |
| 2 | -528 |
| 3 | -4284 |
| 4 | 147712 |
| 5 | -1025850 |
| 6 | 2261952 |
| 7 | 3225992 |
| 8 | -8785920 |
| 9 | -110787507 |
| 10 | 541648800 |
| 11 | -753618228 |
| 12 | -632798208 |
| 13 | 2541064526 |
| 14 | -1703323776 |
| 15 | 4394741400 |
| 16 | -14721941504 |
| 17 | -5429742318 |
| 18 | 58495803696 |
| 19 | 1487499860 |
| 20 | -151530355200 |