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 | 4861 |
| 10 | 16794 |
| 11 | 58763 |
| 12 | 207889 |
| 13 | 742192 |
| 14 | 2670734 |
| 15 | 9676092 |
| 16 | 35265848 |
| 17 | 129205675 |
| 18 | 475578542 |
| 19 | 1757747362 |
| 20 | 6520738724 |
| 21 | 24270689885 |
| 22 | 90609301618 |
| 23 | 339193083093 |
| 24 | 1272910714175 |
| 25 | 4787750073615 |
| 26 | 18045298493265 |
| 27 | 68143016730029 |