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) |
|---|---|
| 4 | 1 |
| 5 | 5 |
| 6 | 31 |
| 7 | 217 |
| 8 | 1737 |
| 9 | 15634 |
| 10 | 156341 |
| 11 | 1719751 |
| 12 | 20637013 |
| 13 | 268281169 |
| 14 | 3755936367 |
| 15 | 56339045506 |
| 16 | 901424728097 |
| 17 | 15324220377649 |
| 18 | 275835966797683 |
| 19 | 5240883369155977 |
| 20 | 104817667383119541 |
| 21 | 2201171015045510362 |