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 | 9 |
| 2 | 33 |
| 3 | 65 |
| 4 | 129 |
| 5 | 2049 |
| 6 | 4097 |
| 7 | 8193 |
| 8 | 131073 |
| 9 | 524289 |
| 10 | 1048577 |
| 11 | 8388609 |
| 12 | 268435457 |
| 13 | 2147483649 |
| 14 | 4294967297 |
| 15 | 1099511627777 |
| 16 | 8796093022209 |
| 17 | 2305843009213693953 |
| 18 | 18446744073709551617 |
| 19 | 604462909807314587353089 |
| 20 | 4951760157141521099596496897 |