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 | 5 |
| 2 | 56 |
| 3 | 492 |
| 4 | 3936 |
| 5 | 30710 |
| 6 | 240012 |
| 7 | 1904301 |
| 8 | 15446672 |
| 9 | 128576019 |
| 10 | 1100414420 |
| 11 | 9692024727 |
| 12 | 87872444424 |
| 13 | 820015945853 |
| 14 | 7873581959208 |
| 15 | 77748058644050 |
| 16 | 789084769234176 |
| 17 | 8226289694091564 |
| 18 | 88033961164032132 |
| 19 | 966450255695509761 |
| 20 | 10877046448539404200 |