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) |
|---|---|
| 1 | -1 |
| 2 | 2 |
| 3 | 4 |
| 4 | -56 |
| 5 | 80 |
| 6 | -352 |
| 7 | 64 |
| 8 | 2176 |
| 9 | -4864 |
| 10 | 31232 |
| 11 | -23552 |
| 12 | -14336 |
| 13 | 217088 |
| 14 | -2056192 |
| 15 | 2375680 |
| 16 | -7307264 |
| 17 | -4390912 |
| 18 | 102367232 |
| 19 | -169607168 |
| 20 | 877133824 |
| 21 | -397410304 |
| 22 | -3042967552 |
| 23 | 9265217536 |
| 24 | -68308434944 |
| 25 | 62495129600 |
| 26 | -78483816448 |
| 27 | -342993403904 |