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 | 0 |
| 2 | 12 |
| 3 | 66 |
| 4 | 513 |
| 5 | 514 |
| 6 | 4097 |
| 7 | 4124 |
| 8 | 32769 |
| 9 | 32779 |
| 10 | 32868 |
| 11 | 262145 |
| 12 | 262148 |
| 13 | 262291 |
| 14 | 2097153 |
| 15 | 2097155 |
| 16 | 2097227 |
| 17 | 16777217 |
| 18 | 16777218 |
| 19 | 16777219 |
| 20 | 16782116 |
| 21 | 134217729 |
| 22 | 134217731 |
| 23 | 134217739 |
| 24 | 134218315 |
| 25 | 134219007 |
| 26 | 1073741825 |
| 27 | 1073741826 |