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 | 4 |
| 3 | 1134 |
| 4 | 333132800 |
| 5 | 1319947441510156250 |
| 6 | 876533819183888230348458418944000 |
| 7 | 1185269534290897564185384010731432113450477770983533184 |