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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 9 |
| 4 | 93 |
| 5 | 1155 |
| 6 | 17025 |
| 7 | 292383 |
| 8 | 5752131 |
| 9 | 127790505 |
| 10 | 3167896005 |
| 11 | 86756071545 |
| 12 | 2602658092419 |
| 13 | 84917405260779 |
| 14 | 2994675198208785 |
| 15 | 113538315994418175 |
| 16 | 4606094297461892895 |
| 17 | 199122610252964803857 |
| 18 | 9139190793845641425261 |
| 19 | 443881600924216704982425 |