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 | 1 |
| 1 | -2 |
| 2 | 3 |
| 3 | -5 |
| 4 | 9 |
| 5 | -17 |
| 6 | 33 |
| 7 | -65 |
| 8 | 129 |
| 9 | -257 |
| 10 | 513 |
| 11 | -1025 |
| 12 | 2049 |
| 13 | -4097 |
| 14 | 8193 |
| 15 | -16385 |
| 16 | 32769 |
| 17 | -65537 |
| 18 | 131073 |
| 19 | -262145 |
| 20 | 524289 |
| 21 | -1048577 |
| 22 | 2097153 |
| 23 | -4194305 |
| 24 | 8388609 |
| 25 | -16777217 |
| 26 | 33554433 |
| 27 | -67108865 |
| 28 | 134217729 |
| 29 | -268435457 |
| 30 | 536870913 |