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 | 6 |
| 3 | 40 |
| 4 | 860 |
| 5 | 63000 |
| 6 | 14714728 |
| 7 | 10562062112 |
| 8 | 22960880409360 |
| 9 | 150300904214651680 |
| 10 | 2955814683617734854752 |
| 11 | 174481716707875308905153664 |
| 12 | 30905247968182392588500030233024 |