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 | 1 |
| 2 | 2 |
| 3 | 48 |
| 4 | 1680384 |
| 5 | 14807804035657359360 |
| 6 | 141377911697227887117195970316200795630205476957716480 |