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 | 16796 |
| 11 | 58785 |
| 12 | 208010 |
| 13 | 742873 |
| 14 | 2674282 |
| 15 | 9693840 |
| 16 | 35351966 |
| 17 | 129613793 |
| 18 | 477477188 |
| 19 | 1766446640 |
| 20 | 6560091544 |
| 21 | 24446776958 |
| 22 | 91389820234 |
| 23 | 342624437057 |
| 24 | 1287886748877 |
| 25 | 4852692487519 |
| 26 | 18325298874477 |
| 27 | 69344013520559 |