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 | 0 |
| 1 | 2 |
| 2 | -1 |
| 3 | 4 |
| 4 | -2 |
| 5 | 8 |
| 6 | -4 |
| 7 | 16 |
| 8 | -8 |
| 9 | 32 |
| 10 | -16 |
| 11 | 64 |
| 12 | -32 |
| 13 | 128 |
| 14 | -64 |
| 15 | 256 |
| 16 | -128 |
| 17 | 512 |
| 18 | -256 |
| 19 | 1024 |
| 20 | -512 |
| 21 | 2048 |
| 22 | -1024 |
| 23 | 4096 |
| 24 | -2048 |
| 25 | 8192 |
| 26 | -4096 |
| 27 | 16384 |
| 28 | -8192 |
| 29 | 32768 |
| 30 | -16384 |
| 31 | 65536 |
| 32 | -32768 |
| 33 | 131072 |
| 34 | -65536 |
| 35 | 262144 |
| 36 | -131072 |
| 37 | 524288 |
| 38 | -262144 |
| 39 | 1048576 |
| 40 | -524288 |