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 | 1 |
| 3 | 3 |
| 4 | 17 |
| 5 | 85 |
| 6 | 449 |
| 7 | 3143 |
| 8 | 26529 |
| 9 | 238761 |
| 10 | 2337089 |
| 11 | 25707979 |
| 12 | 311198513 |
| 13 | 4045580669 |
| 14 | 56438768385 |
| 15 | 846581525775 |
| 16 | 13564695924545 |
| 17 | 230599830717265 |
| 18 | 4148392073235329 |
| 19 | 78819449391471251 |
| 20 | 1576759359017662545 |
| 21 | 33111946539370913445 |
| 22 | 728393474991766957889 |