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 | 2 |
| 3 | 4 |
| 4 | -16 |
| 5 | -32 |
| 6 | 272 |
| 7 | 544 |
| 8 | -7936 |
| 9 | -15872 |
| 10 | 353792 |
| 11 | 707584 |
| 12 | -22368256 |
| 13 | -44736512 |
| 14 | 1903757312 |
| 15 | 3807514624 |
| 16 | -209865342976 |
| 17 | -419730685952 |
| 18 | 29088885112832 |
| 19 | 58177770225664 |
| 20 | -4951498053124096 |
| 21 | -9902996106248192 |
| 22 | 1015423886506852352 |