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 | -12 |
| 3 | 240 |
| 4 | 7056 |
| 5 | -1472640 |
| 6 | 60785472 |
| 7 | 24634471680 |
| 8 | -6666732039936 |
| 9 | -266945607045120 |
| 10 | 818181307311879168 |
| 11 | -225753930347735961600 |
| 12 | -114700401016766429097984 |
| 13 | 133755245359458345703342080 |