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 | 15 |
| 5 | 52 |
| 6 | 202 |
| 7 | 855 |
| 8 | 3845 |
| 9 | 18002 |
| 10 | 86472 |
| 11 | 422005 |
| 12 | 2079475 |
| 13 | 10306752 |
| 14 | 51263942 |
| 15 | 255514355 |
| 16 | 1275163905 |
| 17 | 6368612302 |
| 18 | 31821472612 |
| 19 | 159042661905 |
| 20 | 795019337135 |
| 21 | 3974515030652 |
| 22 | 19870830712482 |
| 23 | 99348921288655 |