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 | 0 |
| 2 | -1 |
| 3 | -4 |
| 4 | -39 |
| 5 | -680 |
| 6 | -18425 |
| 7 | -713820 |
| 8 | -37390255 |
| 9 | -2543067280 |
| 10 | -217799766225 |
| 11 | -22928327328500 |
| 12 | -2909576503498775 |
| 13 | -437960283393276600 |
| 14 | -77145678498655849225 |
| 15 | -15720035935018890359500 |
| 16 | -3668950667796545284209375 |
| 17 | -972327797466833893742228000 |