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 | 2 |
| 2 | 4 |
| 3 | -24 |
| 4 | 400 |
| 5 | -5600 |
| 6 | -103872 |
| 7 | 26975872 |
| 8 | -3438685952 |
| 9 | 417995260416 |
| 10 | -51382607559680 |
| 11 | 5994623640856576 |
| 12 | -454930757753597952 |
| 13 | -94991612229069430784 |
| 14 | 81515752167646959124480 |
| 15 | -41079088828539119883878400 |
| 16 | 18870487103065970636941754368 |
| 17 | -8553231336572387307575081566208 |