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 | -2 |
| 3 | 6 |
| 4 | 24 |
| 5 | -24 |
| 6 | 24 |
| 7 | -240 |
| 8 | 120 |
| 9 | -720 |
| 10 | 2400 |
| 11 | -720 |
| 12 | -720 |
| 13 | 15120 |
| 14 | -25200 |
| 15 | 5040 |
| 16 | 40320 |
| 17 | -282240 |
| 18 | 282240 |
| 19 | -40320 |
| 20 | 40320 |
| 21 | -1451520 |
| 22 | 5080320 |
| 23 | -3386880 |
| 24 | 362880 |
| 25 | -3628800 |
| 26 | 43545600 |
| 27 | -91445760 |
| 28 | 43545600 |
| 29 | -3628800 |
| 30 | -3628800 |
| 31 | 199584000 |
| 32 | -1197504000 |