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 | 14 |
| 3 | -40 |
| 4 | 80 |
| 5 | -64 |
| 6 | -16 |
| 7 | -1600 |
| 8 | 8960 |
| 9 | 29696 |
| 10 | -349696 |
| 11 | -1423360 |
| 12 | 22384640 |
| 13 | 89440256 |
| 14 | -1903691776 |
| 15 | -7615160320 |
| 16 | 209865605120 |
| 17 | 839460847616 |
| 18 | -29088884064256 |
| 19 | -116355542548480 |
| 20 | 4951498057318400 |
| 21 | 19805992204107776 |
| 22 | -1015423886490075136 |