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 | 1 |
| 2 | 4 |
| 3 | 56 |
| 4 | 5712 |
| 5 | 18786768 |
| 6 | 955776822000 |
| 7 | 744550144338000 |
| 8 | 187882017072683934000 |
| 9 | 114232266380191831872000 |
| 10 | 1559289924571192031300084690688000 |