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 | 207999 |
| 13 | 742795 |
| 14 | 2673760 |
| 15 | 9690969 |
| 16 | 35337321 |
| 17 | 129543843 |
| 18 | 477158000 |
| 19 | 1765043115 |
| 20 | 6554105415 |
| 21 | 24421914855 |
| 22 | 91289026931 |
| 23 | 342225162126 |
| 24 | 1286341683924 |
| 25 | 4846861938006 |
| 26 | 18303921153521 |
| 27 | 69268371485362 |
| 28 | 262644901975126 |