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 | 0 |
| 3 | -2 |
| 4 | 8 |
| 5 | -24 |
| 6 | -16 |
| 7 | -720 |
| 8 | 12032 |
| 9 | 0 |
| 10 | -7936 |
| 11 | -3628800 |
| 12 | -58190848 |
| 13 | -479001600 |
| 14 | -22368256 |
| 15 | 87178291200 |
| 16 | 6174957043712 |
| 17 | -20922789888000 |
| 18 | 47215125069824 |
| 19 | -6402373705728000 |
| 20 | -164824694455533568 |
| 21 | 2432902008176640000 |
| 22 | -4951498053124096 |
| 23 | -1124000727777607680000 |