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 | 1 |
| 2 | 2 |
| 3 | 11 |
| 4 | 56 |
| 5 | 401 |
| 6 | 2960 |
| 7 | 23909 |
| 8 | 199324 |
| 9 | 1704937 |
| 10 | 14871560 |
| 11 | 131002444 |
| 12 | 1162055526 |
| 13 | 10330588405 |
| 14 | 91813523884 |
| 15 | 814261196562 |
| 16 | 7195489202430 |
| 17 | 63317110066321 |
| 18 | 554812081610114 |
| 19 | 4845145547265182 |
| 20 | 42242647963009666 |
| 21 | 368598374017590156 |
| 22 | 3228911122031762918 |