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 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 132 |
| 7 | 429 |
| 8 | 1430 |
| 9 | 4862 |
| 10 | 16795 |
| 11 | 58784 |
| 12 | 207987 |
| 13 | 742760 |
| 14 | 2673592 |
| 15 | 9690220 |
| 16 | 35333404 |
| 17 | 129522165 |
| 18 | 477035494 |
| 19 | 1764359882 |
| 20 | 6550391672 |
| 21 | 24402303601 |
| 22 | 91188289504 |
| 23 | 341720434791 |
| 24 | 1283867554724 |
| 25 | 4834962472637 |
| 26 | 18247627360326 |
| 27 | 69005857450243 |