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 | 0 |
| 3 | -2 |
| 4 | 1 |
| 5 | -3 |
| 6 | 4 |
| 7 | 10 |
| 8 | 93 |
| 9 | 8641 |
| 10 | 74666872 |
| 11 | 5575141774264374 |
| 12 | 31082205803147712138788845611865 |
| 13 | 966103517589229313003894215813508352493573272034098666228778213 |