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 | 2 |
| 2 | 40 |
| 3 | 1632 |
| 4 | 140128 |
| 5 | 42396096 |
| 6 | 71916221184 |
| 7 | 569069398642688 |
| 8 | 18501543711357418496 |
| 9 | 2419851465592233142433792 |