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 | 0 |
| 1 | 0 |
| 2 | 3 |
| 3 | -51 |
| 4 | 1059 |
| 5 | -23090 |
| 6 | 522721 |
| 7 | -12147685 |
| 8 | 287854454 |
| 9 | -6924261148 |
| 10 | 168559758222 |
| 11 | -4143307764311 |
| 12 | 102667574424349 |
| 13 | -2561308686267644 |
| 14 | 64269232404321663 |
| 15 | -1620744761933019015 |
| 16 | 41050609554433557263 |
| 17 | -1043736712034774976330 |
| 18 | 26628094150076388266301 |