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 | 13 |
| 5 | 35 |
| 6 | 135 |
| 7 | 613 |
| 8 | 3624 |
| 9 | 25230 |
| 10 | 203640 |
| 11 | 1842350 |
| 12 | 18535683 |
| 13 | 204650313 |