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 | 1 |
| 3 | 3 |
| 4 | 21 |
| 5 | 987 |
| 6 | 2178309 |
| 7 | 10610209857723 |
| 8 | 155576970220531065681649693 |
| 9 | 33449372971981195681356806732944396691005381570580873 |