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 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 110 |
| 6 | 630 |
| 7 | 4204 |
| 8 | 32054 |
| 9 | 274914 |
| 10 | 2619692 |
| 11 | 27459344 |
| 12 | 313990182 |
| 13 | 3889585408 |
| 14 | 51888955808 |
| 15 | 741668212080 |
| 16 | 11307669002720 |
| 17 | 183174676857608 |
| 18 | 3141820432768752 |
| 19 | 56882461258572976 |
| 20 | 1084056190235653304 |
| 21 | 21692744773505849952 |
| 22 | 454758269790599361968 |