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 | 3 |
| 2 | 16 |
| 3 | 104 |
| 4 | 750 |
| 5 | 5769 |
| 6 | 46373 |
| 7 | 384885 |
| 8 | 3273118 |
| 9 | 28372354 |
| 10 | 249762585 |
| 11 | 2226782078 |
| 12 | 20065651123 |
| 13 | 182457467898 |
| 14 | 1672073116401 |
| 15 | 15427427247088 |
| 16 | 143191280370438 |
| 17 | 1336062703751262 |
| 18 | 12524930325385008 |
| 19 | 117910257665608080 |
| 20 | 1114233543986585741 |