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) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 340 |
| 4 | 56496 |
| 5 | 28645840 |
| 6 | 20091622560 |
| 7 | 29056095714720 |
| 8 | 52981034285587200 |
| 9 | 165795456023776938240 |