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 | 9 |
| 3 | 64 |
| 4 | 425 |
| 5 | 2751 |
| 6 | 17640 |
| 7 | 112848 |
| 8 | 722601 |
| 9 | 4638205 |
| 10 | 29860259 |
| 11 | 192831288 |
| 12 | 1248973544 |
| 13 | 8112024844 |
| 14 | 52820112480 |
| 15 | 344712308064 |
| 16 | 2254247833257 |
| 17 | 14768735480505 |
| 18 | 96917273443305 |
| 19 | 636948624057900 |
| 20 | 4191706659276675 |
| 21 | 27618897144488595 |
| 22 | 182181063882796680 |