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 | 1 |
| 3 | -3 |
| 4 | 11 |
| 5 | -45 |
| 6 | 175 |
| 7 | -315 |
| 8 | -6265 |
| 9 | 139755 |
| 10 | -2127125 |
| 11 | 28153125 |
| 12 | -327452125 |
| 13 | 2921393475 |
| 14 | -2998820825 |
| 15 | -788463550875 |
| 16 | 28464750689375 |
| 17 | -739460838241125 |
| 18 | 16173782241491875 |
| 19 | -294957734383186875 |
| 20 | 3672958879661946875 |
| 21 | 19544468129733421875 |
| 22 | -3601613031568517590625 |