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 | -5 |
| 3 | -48 |
| 4 | 660 |
| 5 | 11760 |
| 6 | -257040 |
| 7 | -6652800 |
| 8 | 198918720 |
| 9 | 6745939200 |
| 10 | -255826771200 |
| 11 | -10727081164800 |
| 12 | 492775291008000 |
| 13 | 24610605962342400 |
| 14 | -1327677426915840000 |
| 15 | -76940526008586240000 |
| 16 | 4766815315895592960000 |
| 17 | 314406967644177408000000 |
| 18 | -21995911456386651463680000 |