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 | 1 |
| 2 | 13 |
| 3 | 127 |
| 4 | 1105 |
| 5 | 9031 |
| 6 | 70993 |
| 7 | 543607 |
| 8 | 4085185 |
| 9 | 30275911 |
| 10 | 222009073 |
| 11 | 1614529687 |
| 12 | 11664504865 |
| 13 | 83828316391 |
| 14 | 599858908753 |
| 15 | 4277376525367 |
| 16 | 30411820662145 |
| 17 | 215703854542471 |
| 18 | 1526853641242033 |
| 19 | 10789535445362647 |