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 | 1 |
| 3 | 4 |
| 4 | 16 |
| 5 | 153 |
| 6 | 71838 |
| 7 | 5965398 |
| 8 | 2614508085 |
| 9 | 9822629511079 |
| 10 | 28751930151895611 |
| 11 | 162231215752303027270 |
| 12 | 32813942272624544838651213 |
| 13 | 1257159787425487037702548758466 |