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 | 15 |
| 2 | 89 |
| 3 | 567 |
| 4 | 3713 |
| 5 | 24615 |
| 6 | 164369 |
| 7 | 1103607 |
| 8 | 7444673 |
| 9 | 50431815 |
| 10 | 342942449 |
| 11 | 2340125847 |
| 12 | 16018073633 |
| 13 | 109949712615 |
| 14 | 756587253329 |
| 15 | 5217746527287 |
| 16 | 36054040542593 |
| 17 | 249557173563015 |
| 18 | 1729973554841009 |
| 19 | 12008254925907927 |