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 | 5 |
| 3 | 42 |
| 4 | 514 |
| 5 | 7815 |
| 6 | 139971 |
| 7 | 2882404 |
| 8 | 67108868 |
| 9 | 1743392205 |
| 10 | 50000000005 |
| 11 | 1569214188366 |
| 12 | 53496602689542 |
| 13 | 1968688192849651 |
| 14 | 77784047778906119 |
| 15 | 3284204177856445320 |
| 16 | 147573952589676412936 |
| 17 | 7031542226033862495513 |