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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 28 |
| 4 | 132 |
| 5 | 695 |
| 6 | 4226 |
| 7 | 29666 |
| 8 | 237448 |
| 9 | 2137197 |
| 10 | 21372190 |
| 11 | 235094376 |
| 12 | 2821132876 |
| 13 | 36674727843 |
| 14 | 513446190362 |
| 15 | 7701692856110 |
| 16 | 123227085698576 |
| 17 | 2094860456876761 |
| 18 | 37707488223782838 |
| 19 | 716442276251875252 |
| 20 | 14328845525037506580 |
| 21 | 300905756025787639951 |
| 22 | 6619926632567328080946 |