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 | 4 |
| 3 | 22 |
| 4 | 141 |
| 5 | 973 |
| 6 | 7112 |
| 7 | 54040 |
| 8 | 422552 |
| 9 | 3377770 |
| 10 | 27478568 |
| 11 | 226753828 |
| 12 | 1893462584 |
| 13 | 15969598554 |
| 14 | 135842638632 |
| 15 | 1164075017512 |
| 16 | 10039732285528 |
| 17 | 87081507756245 |
| 18 | 759128176746864 |
| 19 | 6647475055207618 |
| 20 | 58445784269830824 |
| 21 | 515745587816906733 |