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) |
|---|---|
| 3 | 1 |
| 4 | -20 |
| 5 | 610 |
| 6 | -15860 |
| 7 | 433771 |
| 8 | -11662040 |
| 9 | 315323620 |
| 10 | -8509702520 |
| 11 | 229798289941 |
| 12 | -6204226946060 |
| 13 | 167517069529030 |
| 14 | -4522934399547980 |
| 15 | 122119467087816511 |
| 16 | -3297223466672052080 |
| 17 | 89025052902439936840 |
| 18 | -2403676254645238280240 |