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 | 7 |
| 2 | 42 |
| 3 | 203 |
| 4 | 889 |
| 5 | 3535 |
| 6 | 13209 |
| 7 | 46551 |
| 8 | 156905 |
| 9 | 507787 |
| 10 | 1588594 |
| 11 | 4819003 |
| 12 | 14231294 |
| 13 | 41007134 |
| 14 | 115589904 |
| 15 | 319284693 |
| 16 | 865781826 |
| 17 | 2307766118 |
| 18 | 6054769679 |
| 19 | 15652436765 |
| 20 | 39909873983 |
| 21 | 100451866962 |