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 | 0 |
| 2 | -1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 7 |
| 7 | 46 |
| 8 | 2109 |
| 9 | 4447835 |
| 10 | 19783236185116 |
| 11 | 391376433956083065015485621 |
| 12 | 153175513056180249189030531428945090978436751221570525 |