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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 3 |
| 7 | 11 |
| 8 | 38 |
| 9 | 156 |
| 10 | 638 |
| 11 | 2973 |
| 12 | 13882 |
| 13 | 67868 |
| 14 | 338147 |
| 15 | 1720303 |
| 16 | 8905996 |
| 17 | 46774728 |
| 18 | 248918004 |
| 19 | 1340083514 |
| 20 | 7288922610 |
| 21 | 40019870539 |
| 22 | 221582395052 |
| 23 | 1236358849827 |