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 | 0 |
| 1 | 1 |
| 2 | 8 |
| 3 | 48 |
| 4 | 256 |
| 5 | 1280 |
| 6 | 6144 |
| 7 | 28672 |
| 8 | 131072 |
| 9 | 589824 |
| 10 | 2621440 |
| 11 | 11534336 |
| 12 | 50331648 |
| 13 | 218103808 |
| 14 | 939524096 |
| 15 | 4026531840 |
| 16 | 17179869184 |
| 17 | 73014444032 |
| 18 | 309237645312 |
| 19 | 1305670057984 |
| 20 | 5497558138880 |
| 21 | 23089744183296 |