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) |
|---|---|
| 1 | 4 |
| 2 | 1440 |
| 3 | 18808672 |
| 4 | 13140301136292 |
| 5 | 552399762979005094984 |
| 6 | 1425253513627334593833784280100 |