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 | 3 |
| 1 | 3 |
| 2 | 9 |
| 3 | 55 |
| 4 | 513 |
| 5 | 6251 |
| 6 | 93313 |
| 7 | 1647087 |
| 8 | 33554433 |
| 9 | 774840979 |
| 10 | 20000000001 |
| 11 | 570623341223 |
| 12 | 17832200896513 |
| 13 | 605750213184507 |
| 14 | 22224013651116033 |
| 15 | 875787780761718751 |
| 16 | 36893488147419103233 |
| 17 | 1654480523772673528355 |
| 18 | 78692816150593075150849 |
| 19 | 3956839311320627178247959 |