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 | 55 |
| 6 | 232 |
| 7 | 1161 |
| 8 | 6643 |
| 9 | 44566 |
| 10 | 327064 |
| 11 | 2709050 |
| 12 | 24312028 |
| 13 | 240833770 |
| 14 | 2546215687 |
| 15 | 29251369570 |
| 16 | 355838858402 |
| 17 | 4658866773664 |
| 18 | 64127566159756 |
| 19 | 940320691236206 |