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 | 58774 |
| 12 | 207921 |
| 13 | 742340 |
| 14 | 2671380 |
| 15 | 9679341 |
| 16 | 35283057 |
| 17 | 129298686 |
| 18 | 476076425 |
| 19 | 1760356290 |
| 20 | 6534075415 |
| 21 | 24337242771 |
| 22 | 90934212636 |
| 23 | 340748853950 |
| 24 | 1280234838924 |
| 25 | 4821722837721 |
| 26 | 18200855131046 |
| 27 | 68847269742844 |
| 28 | 260929422296290 |