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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 30 |
| 5 | 186 |
| 6 | 1197 |
| 7 | 7953 |
| 8 | 54233 |
| 9 | 377697 |
| 10 | 2676006 |
| 11 | 19230738 |
| 12 | 139850889 |
| 13 | 1027326257 |
| 14 | 7612046713 |
| 15 | 56825410753 |
| 16 | 426995181354 |
| 17 | 3227048864886 |
| 18 | 24513726327089 |
| 19 | 187067287095441 |
| 20 | 1433409279614225 |
| 21 | 11024386107439141 |
| 22 | 85075022074507194 |