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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 75 |
| 5 | 541 |
| 6 | 4683 |
| 7 | 47292 |
| 8 | 545819 |
| 9 | 7086973 |
| 10 | 102242283 |
| 11 | 1622530933 |
| 12 | 28089498891 |
| 13 | 526813752973 |
| 14 | 10640325166227 |
| 15 | 230258631645913 |
| 16 | 5315029292965675 |
| 17 | 130353994525735677 |
| 18 | 3385061859378821547 |
| 19 | 92787606222541942477 |
| 20 | 2677254928352340708075 |
| 21 | 81110818086045534369661 |