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 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 71 |
| 6 | 391 |
| 7 | 2836 |
| 8 | 21729 |
| 9 | 198829 |
| 10 | 1939501 |
| 11 | 21515836 |
| 12 | 254169301 |
| 13 | 3319328299 |
| 14 | 45979476635 |
| 15 | 691443303916 |
| 16 | 10979537304961 |
| 17 | 186915474027321 |
| 18 | 3345563762493049 |
| 19 | 63613875064443796 |
| 20 | 1266776073045809341 |