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 | -1 |
| 2 | -2 |
| 3 | 0 |
| 4 | 8 |
| 5 | 0 |
| 6 | -32 |
| 7 | 0 |
| 8 | 128 |
| 9 | 0 |
| 10 | -512 |
| 11 | 0 |
| 12 | 2048 |
| 13 | 0 |
| 14 | -8192 |
| 15 | 0 |
| 16 | 32768 |
| 17 | 0 |
| 18 | -131072 |
| 19 | 0 |
| 20 | 524288 |
| 21 | 0 |
| 22 | -2097152 |
| 23 | 0 |
| 24 | 8388608 |
| 25 | 0 |
| 26 | -33554432 |
| 27 | 0 |
| 28 | 134217728 |
| 29 | 0 |
| 30 | -536870912 |
| 31 | 0 |
| 32 | 2147483648 |
| 33 | 0 |
| 34 | -8589934592 |
| 35 | 0 |
| 36 | 34359738368 |
| 37 | 0 |
| 38 | -137438953472 |
| 39 | 0 |
| 40 | 549755813888 |
| 41 | 0 |
| 42 | -2199023255552 |