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) |
|---|---|
| 4 | 1 |
| 5 | 40 |
| 6 | 1092 |
| 7 | 25664 |
| 8 | 561104 |
| 9 | 11807616 |
| 10 | 243248704 |
| 11 | 4950550528 |
| 12 | 100040447232 |
| 13 | 2013177300992 |
| 14 | 40412056994816 |
| 15 | 810023815790592 |
| 16 | 16221871691714560 |
| 17 | 324694197936160768 |
| 18 | 6496965245491888128 |
| 19 | 129976281056339296256 |