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 | 6 |
| 3 | 75 |
| 4 | 1448 |
| 5 | 38020 |
| 6 | 1265454 |
| 7 | 51069326 |
| 8 | 2423671144 |
| 9 | 132284727792 |
| 10 | 8164129781280 |
| 11 | 562204918658592 |
| 12 | 42737232766827576 |
| 13 | 3554783958154270608 |
| 14 | 321149971312286643240 |
| 15 | 31316069883727673961240 |