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 | 3 |
| 2 | 9 |
| 3 | 81 |
| 4 | 21 |
| 5 | 1359 |
| 6 | 2727 |
| 7 | 21837 |
| 8 | 21843 |
| 9 | 349515 |
| 10 | 699045 |
| 11 | 5592393 |
| 12 | 2796201 |
| 13 | 89478471 |
| 14 | 178956963 |
| 15 | 1431655749 |
| 16 | 1431655761 |
| 17 | 22906492227 |
| 18 | 45812984481 |
| 19 | 366503875905 |
| 20 | 22906492245 |
| 21 | 5864062014783 |
| 22 | 11728124029599 |
| 23 | 93824992236861 |
| 24 | 93824992236879 |
| 25 | 1501199875790139 |