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 | 144 |
| 4 | 331776 |
| 5 | 2751882854400 |
| 6 | 272622932796264897576960000 |
| 7 | 3641839910835401567626683591527643364677019238400000000 |