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 | 2 |
| 3 | 0 |
| 4 | 12 |
| 5 | -26 |
| 6 | 312 |
| 7 | -1338 |
| 8 | 16684 |
| 9 | -104994 |
| 10 | 1463904 |
| 11 | -12138218 |
| 12 | 190104132 |
| 13 | -1956240066 |
| 14 | 34206491416 |
| 15 | -420374124426 |
| 16 | 8140714373532 |
| 17 | -116318340148898 |
| 18 | 2474986205007504 |
| 19 | -40312051604277354 |