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 | 2 |
| 3 | 6 |
| 4 | 36 |
| 5 | 144 |
| 6 | 1152 |
| 7 | 13824 |
| 8 | 248832 |
| 9 | 2488320 |
| 10 | 39813120 |
| 11 | 796262400 |
| 12 | 19906560000 |
| 13 | 378224640000 |
| 14 | 10212065280000 |
| 15 | 91908587520000 |
| 16 | 3308709150720000 |
| 17 | 79409019617280000 |
| 18 | 2382270588518400000 |
| 19 | 35734058827776000000 |