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 | 1 |
| 3 | 0 |
| 4 | 3 |
| 5 | 1 |
| 6 | 15 |
| 7 | 15 |
| 8 | 105 |
| 9 | 190 |
| 10 | 945 |
| 11 | 2410 |
| 12 | 10263 |
| 13 | 31890 |
| 14 | 127699 |
| 15 | 444458 |
| 16 | 1751685 |
| 17 | 6518736 |
| 18 | 25807445 |
| 19 | 100152288 |
| 20 | 401449271 |
| 21 | 1602902055 |
| 22 | 6519160851 |
| 23 | 26580508625 |
| 24 | 109656966853 |
| 25 | 454524861846 |
| 26 | 1899821492925 |
| 27 | 7982263725826 |
| 28 | 33757439931675 |