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 | 20 |
| 3 | 1680 |
| 4 | 354624 |
| 5 | 151213748 |
| 6 | 114062310060 |
| 7 | 139028830444866 |
| 8 | 256400413791435360 |
| 9 | 680598969845995094212 |
| 10 | 2500271405904975564019712 |