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 | 9 |
| 2 | 81 |
| 3 | 2187 |
| 4 | 6561 |
| 5 | 59049 |
| 6 | 1594323 |
| 7 | 4782969 |
| 8 | 43046721 |
| 9 | 3486784401 |
| 10 | 3486784401 |
| 11 | 31381059609 |
| 12 | 847288609443 |
| 13 | 2541865828329 |
| 14 | 22876792454961 |
| 15 | 617673396283947 |
| 16 | 1853020188851841 |
| 17 | 16677181699666569 |
| 18 | 1350851717672992089 |
| 19 | 1350851717672992089 |
| 20 | 12157665459056928801 |
| 21 | 328256967394537077627 |