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 | -2040 |
| 5 | 4508570 |
| 6 | -9900819720 |
| 7 | 21752862899691 |
| 8 | -47790911017216080 |
| 9 | 104996653267533662740 |
| 10 | -230677643550873536294640 |
| 11 | 506798783502833908602716981 |
| 12 | -1113436927250681654567602842120 |