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 | 2 |
| 2 | -2 |
| 3 | 30 |
| 4 | -166 |
| 5 | 1514 |
| 6 | -12474 |
| 7 | 114006 |
| 8 | -1050830 |
| 9 | 10005138 |
| 10 | -96772786 |
| 11 | 951500686 |
| 12 | -9469982966 |
| 13 | 95267209850 |
| 14 | -966979784554 |
| 15 | 9891522355270 |
| 16 | -101866781649310 |
| 17 | 1055294818173474 |
| 18 | -10989809960251490 |
| 19 | 114983445265899774 |
| 20 | -1208092406024272710 |