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 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 10 |
| 5 | 37 |
| 6 | 126 |
| 7 | 422 |
| 8 | 1422 |
| 9 | 4853 |
| 10 | 16786 |
| 11 | 58775 |
| 12 | 208000 |
| 13 | 742887 |
| 14 | 2674426 |
| 15 | 9694830 |
| 16 | 35357654 |
| 17 | 129644773 |
| 18 | 477638682 |
| 19 | 1767263171 |
| 20 | 6564120400 |
| 21 | 24466266999 |
| 22 | 91482563618 |
| 23 | 343059613627 |
| 24 | 1289904147300 |
| 25 | 4861946401427 |
| 26 | 18367353072126 |
| 27 | 69533550915977 |
| 28 | 263747951750332 |
| 29 | 1002242216651339 |