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 | 2 |
| 1 | 2 |
| 2 | 6 |
| 3 | 24 |
| 4 | 168 |
| 5 | 1848 |
| 6 | 33264 |
| 7 | 964656 |
| 8 | 45338832 |
| 9 | 3445751232 |
| 10 | 423827401536 |
| 11 | 84341652905664 |
| 12 | 27158012235623808 |
| 13 | 14149324374760003968 |
| 14 | 11927880447922683345024 |
| 15 | 16269628930966540082612736 |