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 | -16 |
| 3 | 288 |
| 4 | -9216 |
| 5 | 460800 |
| 6 | -33177600 |
| 7 | 3251404800 |
| 8 | -416179814400 |
| 9 | 67421129932800 |
| 10 | -13484225986560000 |
| 11 | 3263182688747520000 |
| 12 | -939796614359285760000 |
| 13 | 317651255653438586880000 |
| 14 | -124519292216147926056960000 |
| 15 | 56033681497266566725632000000 |