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 | 0 |
| 2 | 15 |
| 3 | 105 |
| 4 | 2145 |
| 5 | 32640 |
| 6 | 73920 |
| 7 | 1906128 |
| 8 | 2299440 |
| 9 | 7692030528 |