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 | 1 |
| 2 | 11 |
| 3 | 57 |
| 4 | 247 |
| 5 | 1013 |
| 6 | 4083 |
| 7 | 16369 |
| 8 | 65519 |
| 9 | 262125 |
| 10 | 1048555 |
| 11 | 4194281 |
| 12 | 16777191 |
| 13 | 67108837 |
| 14 | 268435427 |
| 15 | 1073741793 |
| 16 | 4294967263 |
| 17 | 17179869149 |
| 18 | 68719476699 |
| 19 | 274877906905 |
| 20 | 1099511627735 |
| 21 | 4398046511061 |
| 22 | 17592186044371 |
| 23 | 70368744177617 |
| 24 | 281474976710607 |
| 25 | 1125899906842573 |