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 | 6 |
| 3 | 13440 |
| 4 | 81729648000 |
| 5 | 4963587213865915514880 |
| 6 | 7973107998754741458076119859200000000 |
| 7 | 738615790595351500616546025309298211371540807680000000000 |