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 | 3 |
| 2 | 6 |
| 3 | 10 |
| 4 | 259200 |
| 5 | 87178291200 |
| 6 | 202741834014720 |
| 7 | 484725313854093312000000 |
| 8 | 4438779300500903005519872000000 |
| 9 | 346902756482949716983678260882702336000000000 |