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) |
|---|---|
| 0 | 2 |
| 1 | 9 |
| 2 | 65 |
| 3 | 513 |
| 4 | 4097 |
| 5 | 32769 |
| 6 | 262145 |
| 7 | 2097153 |
| 8 | 16777217 |
| 9 | 134217729 |
| 10 | 1073741825 |
| 11 | 8589934593 |
| 12 | 68719476737 |
| 13 | 549755813889 |
| 14 | 4398046511105 |
| 15 | 35184372088833 |
| 16 | 281474976710657 |
| 17 | 2251799813685249 |
| 18 | 18014398509481985 |
| 19 | 144115188075855873 |