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 | 5040 |
| 2 | 439378587648000 |
| 3 | 22448266013011335649028997120000000 |
| 4 | 6844214664110424043644485692109939233534721371668480000000000000 |