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 | 0 |
| 2 | -1 |
| 3 | 1 |
| 4 | 1 |
| 5 | -5 |
| 6 | 9 |
| 7 | -9 |
| 8 | 1 |
| 9 | 15 |
| 10 | -31 |
| 11 | 31 |
| 12 | 1 |
| 13 | -65 |
| 14 | 129 |
| 15 | -129 |
| 16 | 1 |
| 17 | 255 |
| 18 | -511 |
| 19 | 511 |
| 20 | 1 |
| 21 | -1025 |
| 22 | 2049 |
| 23 | -2049 |
| 24 | 1 |
| 25 | 4095 |
| 26 | -8191 |
| 27 | 8191 |
| 28 | 1 |
| 29 | -16385 |
| 30 | 32769 |
| 31 | -32769 |
| 32 | 1 |
| 33 | 65535 |
| 34 | -131071 |
| 35 | 131071 |
| 36 | 1 |
| 37 | -262145 |
| 38 | 524289 |
| 39 | -524289 |
| 40 | 1 |
| 41 | 1048575 |
| 42 | -2097151 |
| 43 | 2097151 |
| 44 | 1 |
| 45 | -4194305 |
| 46 | 8388609 |
| 47 | -8388609 |