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 | 0 |
| 3 | -2 |
| 4 | -8 |
| 5 | -24 |
| 6 | 16 |
| 7 | 400 |
| 8 | -3072 |
| 9 | -38528 |
| 10 | -18944 |
| 11 | 1287936 |
| 12 | 17843200 |
| 13 | 149045248 |
| 14 | -188786688 |
| 15 | -12007184384 |
| 16 | -1265929355264 |
| 17 | -20275964313600 |
| 18 | 3871935889408 |
| 19 | 2355175169523712 |
| 20 | 45658709327609856 |
| 21 | 565591105847689216 |
| 22 | -1448855443865600000 |