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 | 1 |
| 2 | 9 |
| 3 | 59 |
| 4 | 335 |
| 5 | 1732 |
| 6 | 8404 |
| 7 | 38969 |
| 8 | 174637 |
| 9 | 762063 |
| 10 | 3255119 |
| 11 | 13662512 |
| 12 | 56511312 |
| 13 | 230859729 |
| 14 | 933104857 |
| 15 | 3736739227 |
| 16 | 14843364031 |
| 17 | 58540883044 |
| 18 | 229411923796 |
| 19 | 893904838857 |
| 20 | 3465221557357 |
| 21 | 13370453635199 |