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 | 4 |
| 1 | 7 |
| 2 | 13 |
| 3 | 25 |
| 4 | 49 |
| 5 | 97 |
| 6 | 193 |
| 7 | 385 |
| 8 | 769 |
| 9 | 1537 |
| 10 | 3073 |
| 11 | 6145 |
| 12 | 12289 |
| 13 | 24577 |
| 14 | 49153 |
| 15 | 98305 |
| 16 | 196609 |
| 17 | 393217 |
| 18 | 786433 |
| 19 | 1572865 |
| 20 | 3145729 |
| 21 | 6291457 |
| 22 | 12582913 |
| 23 | 25165825 |
| 24 | 50331649 |
| 25 | 100663297 |
| 26 | 201326593 |
| 27 | 402653185 |
| 28 | 805306369 |
| 29 | 1610612737 |
| 30 | 3221225473 |