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 | 3 |
| 3 | 9 |
| 4 | 21 |
| 5 | 231 |
| 6 | 847 |
| 7 | 2541 |
| 8 | 16093 |
| 9 | 33649 |
| 10 | 43263 |
| 11 | 447051 |
| 12 | 1043119 |
| 13 | 13560547 |
| 14 | 83300503 |
| 15 | 170222767 |
| 16 | 222599003 |
| 17 | 13133341177 |
| 18 | 774867129443 |
| 19 | 4719645242971 |
| 20 | 335094812250941 |