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) |
|---|---|
| 2 | 2 |
| 3 | 4 |
| 4 | 13 |
| 5 | 61 |
| 6 | 361 |
| 7 | 2521 |
| 8 | 20161 |
| 9 | 181441 |
| 10 | 1814401 |
| 11 | 19958401 |
| 12 | 239500801 |
| 13 | 3113510401 |
| 14 | 43589145601 |
| 15 | 653837184001 |
| 16 | 10461394944001 |
| 17 | 177843714048001 |
| 18 | 3201186852864001 |
| 19 | 60822550204416001 |
| 20 | 1216451004088320001 |
| 21 | 25545471085854720001 |
| 22 | 562000363888803840001 |