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 | 3 |
| 3 | 14 |
| 4 | 73 |
| 5 | 454 |
| 6 | 3253 |
| 7 | 26480 |
| 8 | 241505 |
| 9 | 2440538 |
| 10 | 27075301 |
| 11 | 327197452 |
| 12 | 4278799105 |
| 13 | 60205974230 |
| 14 | 907025841317 |
| 15 | 14567520651224 |
| 16 | 248474458923073 |
| 17 | 4485765986251570 |
| 18 | 85454391074596165 |
| 19 | 1713134893536617348 |
| 20 | 36052727133118151201 |
| 21 | 794697884305583064302 |