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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 8 |
| 6 | 576 |
| 7 | 1152 |
| 8 | 2304 |
| 9 | 4608 |
| 10 | 18432 |
| 11 | 552960 |
| 12 | 59719680 |
| 13 | 2388787200 |
| 14 | 100329062400 |
| 15 | 200658124800 |
| 16 | 802632499200 |
| 17 | 1605264998400 |
| 18 | 288947699712000 |
| 19 | 6356849393664000 |
| 20 | 444979457556480000 |
| 21 | 10679506981355520000 |