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 | 27 |
| 4 | 232 |
| 5 | 2465 |
| 6 | 31416 |
| 7 | 467173 |
| 8 | 7940080 |
| 9 | 151824177 |
| 10 | 3225664720 |
| 11 | 75386002901 |
| 12 | 1921987809336 |
| 13 | 53085088574713 |
| 14 | 1578989028324904 |
| 15 | 50320957240554645 |
| 16 | 1710595789688360416 |
| 17 | 61783832256587799137 |
| 18 | 2362794061464082513440 |
| 19 | 95380148553556615501717 |