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 | 48 |
| 3 | 1567641600 |
| 4 | 9698137182219213471744000000 |
| 5 | 21488900044302744250061179567064173417691432878080000000000000000 |