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 | -1 |
| 2 | -7 |
| 3 | -7 |
| 4 | 17 |
| 5 | 65 |
| 6 | 65 |
| 7 | -127 |
| 8 | -511 |
| 9 | -511 |
| 10 | 1025 |
| 11 | 4097 |
| 12 | 4097 |
| 13 | -8191 |
| 14 | -32767 |
| 15 | -32767 |
| 16 | 65537 |
| 17 | 262145 |
| 18 | 262145 |
| 19 | -524287 |
| 20 | -2097151 |
| 21 | -2097151 |
| 22 | 4194305 |
| 23 | 16777217 |
| 24 | 16777217 |
| 25 | -33554431 |
| 26 | -134217727 |
| 27 | -134217727 |
| 28 | 268435457 |
| 29 | 1073741825 |