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 | 1 |
| 2 | 1 |
| 3 | -3 |
| 4 | -21 |
| 5 | -41 |
| 6 | 166 |
| 7 | 1460 |
| 8 | 3445 |
| 9 | -13503 |
| 10 | -136721 |
| 11 | -364412 |
| 12 | 1285021 |
| 13 | 14694643 |
| 14 | 43144726 |
| 15 | -132548857 |
| 16 | -1709480698 |
| 17 | -5456400119 |
| 18 | 14285376285 |
| 19 | 209281385564 |
| 20 | 720201663662 |
| 21 | -1572818128366 |
| 22 | -26541960203077 |
| 23 | -97918748134874 |
| 24 | 173825501585400 |
| 25 | 3453517916428141 |