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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 91 |
| 6 | 2820 |
| 7 | 177661 |
| 8 | 22562946 |
| 9 | 5753551231 |
| 10 | 2940064679040 |
| 11 | 3007686166657921 |
| 12 | 6156733583148764286 |
| 13 | 25211824022994189751171 |
| 14 | 206510050572345408251841660 |
| 15 | 3383254158526734823389921915781 |