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 | 1 |
| 2 | 3 |
| 3 | 25 |
| 4 | 287 |
| 5 | 4581 |
| 6 | 90519 |
| 7 | 2162901 |
| 8 | 60249195 |
| 9 | 1921751145 |
| 10 | 68980179915 |
| 11 | 2753007869745 |
| 12 | 120897239789655 |