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 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 60 |
| 5 | 377 |
| 6 | 3323 |
| 7 | 42518 |
| 8 | 646580 |
| 9 | 12285485 |
| 10 | 300378113 |
| 11 | 8028681592 |
| 12 | 259488951722 |
| 13 | 9414917934636 |
| 14 | 362597756958862 |
| 15 | 15397728568256861 |
| 16 | 742238179325555125 |
| 17 | 40068968503380861518 |
| 18 | 2251262473065725514585 |
| 19 | 139566579946046888545036 |