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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 10 |
| 5 | 64 |
| 6 | 490 |
| 7 | 4595 |
| 8 | 51063 |
| 9 | 657623 |
| 10 | 9592204 |
| 11 | 155630924 |
| 12 | 2771922417 |
| 13 | 53673859357 |
| 14 | 1121581872170 |
| 15 | 25143397213226 |
| 16 | 601751140758134 |
| 17 | 15310778492310274 |
| 18 | 412656423154230159 |
| 19 | 11743600063060974656 |
| 20 | 351882591907696156959 |