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 | 7 |
| 3 | 17 |
| 4 | 31 |
| 5 | 127 |
| 6 | 257 |
| 7 | 3583 |
| 8 | 5119 |
| 9 | 6143 |
| 10 | 8191 |
| 11 | 65537 |
| 12 | 131071 |
| 13 | 524287 |
| 14 | 7340033 |
| 15 | 14680063 |
| 16 | 104857601 |
| 17 | 109051903 |
| 18 | 167772161 |
| 19 | 469762049 |
| 20 | 2013265921 |
| 21 | 2147483647 |
| 22 | 21474836479 |
| 23 | 51539607551 |
| 24 | 206158430209 |
| 25 | 824633720831 |
| 26 | 2748779069441 |
| 27 | 6597069766657 |
| 28 | 26388279066623 |