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 | 0 |
| 1 | 6 |
| 2 | -120 |
| 3 | 3696 |
| 4 | -168960 |
| 5 | 10830336 |
| 6 | -929510400 |
| 7 | 103028914176 |
| 8 | -14334577213440 |
| 9 | 2446660141449216 |
| 10 | -502760445200302080 |
| 11 | 122445316208597139456 |
| 12 | -34878879321781771960320 |
| 13 | 11489340492300854960848896 |
| 14 | -4333862194374775050243932160 |
| 15 | 1855989889103139616252584001536 |