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 | 1 |
| 2 | 0 |
| 3 | 6 |
| 4 | 36 |
| 5 | -1240 |
| 6 | 36810 |
| 7 | -743568 |
| 8 | -4441640 |
| 9 | 2126086272 |
| 10 | -201265464330 |
| 11 | 13670088101120 |
| 12 | -512174277963612 |
| 13 | -50655591400627200 |
| 14 | 16935777106057251442 |
| 15 | -2936123018591228282880 |
| 16 | 368896773292405165345200 |
| 17 | -22278163772113766968557568 |