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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 28 |
| 4 | 256 |
| 5 | 2704 |
| 6 | 31168 |
| 7 | 380608 |
| 8 | 4840960 |
| 9 | 63458560 |
| 10 | 851399680 |
| 11 | 11635096576 |
| 12 | 161396604928 |
| 13 | 2266669453312 |
| 14 | 32166082822144 |
| 15 | 460531091685376 |
| 16 | 6644185553305600 |
| 17 | 96498260064403456 |
| 18 | 1409750653282287616 |
| 19 | 20702370737659052032 |
| 20 | 305428492830594039808 |