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 | 5 |
| 3 | 63 |
| 4 | 17 |
| 5 | 1023 |
| 6 | 195 |
| 7 | 16383 |
| 8 | 4369 |
| 9 | 262143 |
| 10 | 31775 |
| 11 | 4194303 |
| 12 | 12291 |
| 13 | 67108863 |
| 14 | 89478485 |
| 15 | 1073741823 |
| 16 | 16843009 |
| 17 | 17179869183 |
| 18 | 172229265 |
| 19 | 274877906943 |
| 20 | 6663706835 |
| 21 | 4398046511103 |
| 22 | 254959218035 |
| 23 | 70368744177663 |
| 24 | 206208774147 |
| 25 | 1125899906842623 |
| 26 | 1501199875790165 |