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) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 24 |
| 4 | 80 |
| 5 | 303 |
| 6 | 847 |
| 7 | 3401 |
| 8 | 12816 |
| 9 | 47255 |
| 10 | 168306 |
| 11 | 628058 |
| 12 | 2243714 |
| 13 | 8741445 |
| 14 | 33079519 |
| 15 | 125266470 |
| 16 | 474015314 |
| 17 | 1806320048 |
| 18 | 6945673364 |
| 19 | 26539784794 |
| 20 | 102630867522 |