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 | 3 |
| 3 | 9 |
| 4 | 32 |
| 5 | 126 |
| 6 | 564 |
| 7 | 2700 |
| 8 | 13802 |
| 9 | 74422 |
| 10 | 422812 |
| 11 | 2519962 |
| 12 | 15731562 |
| 13 | 102390662 |
| 14 | 692779852 |
| 15 | 4851392308 |
| 16 | 35068814616 |
| 17 | 261013287116 |
| 18 | 1997276928946 |
| 19 | 15689964298430 |
| 20 | 126416353430344 |
| 21 | 1043615269337354 |
| 22 | 8819704403143576 |
| 23 | 76229300376178238 |
| 24 | 673190822341507644 |