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 | 1 |
| 2 | -3 |
| 3 | 10 |
| 4 | -40 |
| 5 | 205 |
| 6 | -1287 |
| 7 | 9714 |
| 8 | -85384 |
| 9 | 859889 |
| 10 | -9751651 |
| 11 | 123102098 |
| 12 | -1711387808 |
| 13 | 25985945453 |
| 14 | -427828028695 |
| 15 | 7591346835562 |
| 16 | -144408464041712 |
| 17 | 2931676572255297 |
| 18 | -63262735545686819 |
| 19 | 1445955290624608506 |