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 | 1 |
| 1 | 3 |
| 2 | 17 |
| 3 | 99 |
| 4 | 545 |
| 5 | 2883 |
| 6 | 14897 |
| 7 | 75939 |
| 8 | 384065 |
| 9 | 1933443 |
| 10 | 9706577 |
| 11 | 48650979 |
| 12 | 243609185 |
| 13 | 1219108803 |
| 14 | 6098732657 |
| 15 | 30503229219 |
| 16 | 152544843905 |
| 17 | 762810312963 |
| 18 | 3814309845137 |
| 19 | 19072324066659 |
| 20 | 95363944856225 |
| 21 | 476826697849923 |