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 | 5 |
| 4 | 37 |
| 5 | 357 |
| 6 | 4351 |
| 7 | 64243 |
| 8 | 1115899 |
| 9 | 22316409 |
| 10 | 505378207 |
| 11 | 12789077631 |
| 12 | 357769603027 |
| 13 | 10965667062133 |
| 14 | 365497351868767 |
| 15 | 13163965052815515 |
| 16 | 509522144541045811 |
| 17 | 21093278144993719665 |
| 18 | 930067462093579181119 |
| 19 | 43518024090910884374263 |
| 20 | 2153670733766937656155699 |