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 | 0 |
| 2 | 3 |
| 3 | 105 |
| 4 | 4116315 |
| 5 | 9721683943673162520781155 |
| 6 | 35285058531373239343849920668944097883186271103498415 |