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 | 6 |
| 2 | 7 |
| 3 | 11 |
| 4 | 15 |
| 5 | 35 |
| 6 | 39 |
| 7 | 63 |
| 8 | 135 |
| 9 | 255 |
| 10 | 999 |
| 11 | 2175 |
| 12 | 8223 |
| 13 | 16383 |
| 14 | 57735 |
| 15 | 131075 |
| 16 | 131079 |
| 17 | 262143 |
| 18 | 524295 |
| 19 | 1048575 |
| 20 | 536870919 |
| 21 | 1073735679 |
| 22 | 2147483655 |
| 23 | 4294967295 |
| 24 | 17179770879 |
| 25 | 4260641103903 |
| 26 | 4611686018427387903 |
| 27 | 4720069647059686260735 |
| 28 | 1237940039285380274899124223 |