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 | 3 |
| 2 | 9 |
| 3 | 47 |
| 4 | 321 |
| 5 | 2607 |
| 6 | 24099 |
| 7 | 247527 |
| 8 | 2783331 |
| 9 | 33924303 |
| 10 | 445016619 |
| 11 | 6249234807 |
| 12 | 93541817331 |
| 13 | 1487200667103 |
| 14 | 25037315924859 |
| 15 | 445123900236807 |
| 16 | 8336458657796931 |
| 17 | 164100631571947503 |
| 18 | 3388128151043405259 |