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 | 21 |
| 2 | 266 |
| 3 | 2541 |
| 4 | 20097 |
| 5 | 138103 |
| 6 | 849514 |
| 7 | 4771889 |
| 8 | 24828755 |
| 9 | 120944516 |
| 10 | 556107055 |
| 11 | 2429461391 |
| 12 | 10137839293 |
| 13 | 40585353434 |
| 14 | 156451707633 |
| 15 | 582555425669 |
| 16 | 2100914443649 |
| 17 | 7355423560191 |
| 18 | 25050878785976 |
| 19 | 83145222843357 |
| 20 | 269368091719619 |