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 | 6 |
| 3 | 56 |
| 4 | 722 |
| 5 | 12012 |
| 6 | 246092 |
| 7 | 6002824 |
| 8 | 170048394 |
| 9 | 5489377628 |
| 10 | 198966923232 |
| 11 | 8002061191632 |
| 12 | 353657146741108 |
| 13 | 17038311744899928 |
| 14 | 888756685396257456 |
| 15 | 49903123853737160256 |
| 16 | 3001090647251938886634 |
| 17 | 192456294604677056842812 |
| 18 | 13110208254597852188752232 |
| 19 | 945417747582856587884200944 |
| 20 | 71952514694665595216762956518 |
| 21 | 5763451519600988678663191769380 |