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 | 1 |
| 3 | 0 |
| 4 | 6 |
| 5 | 42 |
| 6 | 271 |
| 7 | 2029 |
| 8 | 16880 |
| 9 | 156002 |
| 10 | 1594424 |
| 11 | 17875651 |
| 12 | 217325325 |
| 13 | 2858334613 |
| 14 | 40361092223 |
| 15 | 609787506215 |