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 | 8 |
| 3 | -32 |
| 4 | 128 |
| 5 | -512 |
| 6 | 2048 |
| 7 | -8192 |
| 8 | 32768 |
| 9 | -131072 |
| 10 | 524288 |
| 11 | -2097152 |
| 12 | 8388608 |
| 13 | -33554432 |
| 14 | 134217728 |
| 15 | -536870912 |
| 16 | 2147483648 |
| 17 | -8589934592 |
| 18 | 34359738368 |
| 19 | -137438953472 |
| 20 | 549755813888 |
| 21 | -2199023255552 |
| 22 | 8796093022208 |
| 23 | -35184372088832 |
| 24 | 140737488355328 |
| 25 | -562949953421312 |