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 | 9 |
| 3 | 65 |
| 4 | 521 |
| 5 | 4097 |
| 6 | 32841 |
| 7 | 262145 |
| 8 | 2097673 |
| 9 | 16777281 |
| 10 | 134221833 |
| 11 | 1073741825 |
| 12 | 8589967945 |
| 13 | 68719476737 |
| 14 | 549756076041 |
| 15 | 4398046515265 |
| 16 | 35184374186505 |
| 17 | 281474976710657 |
| 18 | 2251799830495305 |
| 19 | 18014398509481985 |
| 20 | 144115188210078217 |
| 21 | 1152921504607109185 |