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 | 2 |
| 2 | 84 |
| 3 | 8520 |
| 4 | 1681680 |
| 5 | 547011360 |
| 6 | 265419443520 |
| 7 | 179736434317440 |
| 8 | 161969818051641600 |
| 9 | 187420440830701478400 |
| 10 | 270844381564455655756800 |
| 11 | 478068612103265576314521600 |
| 12 | 1012116454555692487808449843200 |
| 13 | 2531390694197068730346648007680000 |