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 | 13 |
| 3 | 91 |
| 4 | 529 |
| 5 | 2851 |
| 6 | 14833 |
| 7 | 75811 |
| 8 | 383809 |
| 9 | 1932931 |
| 10 | 9705553 |
| 11 | 48648931 |
| 12 | 243605089 |
| 13 | 1219100611 |
| 14 | 6098716273 |
| 15 | 30503196451 |
| 16 | 152544778369 |
| 17 | 762810181891 |
| 18 | 3814309582993 |
| 19 | 19072323542371 |
| 20 | 95363943807649 |
| 21 | 476826695752771 |