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 | 9 |
| 2 | 52 |
| 3 | 246 |
| 4 | 1039 |
| 5 | 4083 |
| 6 | 15274 |
| 7 | 55152 |
| 8 | 193957 |
| 9 | 668397 |
| 10 | 2266816 |
| 11 | 7589418 |
| 12 | 25143355 |
| 13 | 82571751 |
| 14 | 269173078 |
| 15 | 871958244 |
| 16 | 2809322833 |
| 17 | 9008574945 |
| 18 | 28768068460 |
| 19 | 91532284830 |
| 20 | 290283189991 |
| 21 | 917912770779 |
| 22 | 2894936303362 |