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 | 4 |
| 2 | 8 |
| 3 | -32 |
| 4 | -160 |
| 5 | 896 |
| 6 | 5376 |
| 7 | -33792 |
| 8 | -219648 |
| 9 | 1464320 |
| 10 | 9957376 |
| 11 | -68796416 |
| 12 | -481574912 |
| 13 | 3408068608 |
| 14 | 24343347200 |
| 15 | -175272099840 |
| 16 | -1270722723840 |
| 17 | 9268801044480 |
| 18 | 67971207659520 |
| 19 | -500840477491200 |
| 20 | -3706219533434880 |
| 21 | 27531916534087680 |
| 22 | 205237923254108160 |