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 | 3 |
| 3 | 18 |
| 4 | 216 |
| 5 | 6840 |
| 6 | 228960 |
| 7 | 15573600 |
| 8 | 994533120 |
| 9 | 85232891520 |
| 10 | 8641918252800 |
| 11 | 1068888956889600 |
| 12 | 155398203460684800 |
| 13 | 26564263279602048000 |