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 | 1 |
| 3 | 240 |
| 4 | 304819200 |
| 5 | 3440500260470784000 |
| 6 | 1827912356210202139164672000000000 |
| 7 | 13482302715547740229948201750717130814259200000000000 |