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 | -5 |
| 2 | 35 |
| 3 | -185 |
| 4 | 1235 |
| 5 | -6785 |
| 6 | 43835 |
| 7 | -247385 |
| 8 | 1562435 |
| 9 | -8983985 |
| 10 | 55857035 |
| 11 | -325376585 |
| 12 | 2001087635 |
| 13 | -11762385185 |
| 14 | 71795014235 |
| 15 | -424666569785 |
| 16 | 2578516996835 |
| 17 | -15318514090385 |
| 18 | 92674023995435 |
| 19 | -552229446706985 |