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 | 3 |
| 3 | 13 |
| 4 | 75 |
| 5 | 541 |
| 6 | 4682 |
| 7 | 47279 |
| 8 | 545611 |
| 9 | 7083565 |
| 10 | 102182883 |
| 11 | 1621425829 |
| 12 | 28067555607 |
| 13 | 526349480593 |
| 14 | 10629883138059 |
| 15 | 230009622202373 |
| 16 | 5308749619032571 |
| 17 | 130186940173803053 |
| 18 | 3380385112758108315 |
| 19 | 92650130825921846941 |
| 20 | 2673020491585091254035 |
| 21 | 80974418589343644492805 |