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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 49 |
| 5 | 441 |
| 6 | 4806 |
| 7 | 52956 |
| 8 | 614713 |
| 9 | 7341697 |
| 10 | 90118054 |
| 11 | 1130414649 |
| 12 | 14447230854 |
| 13 | 187609607862 |
| 14 | 2470253990556 |
| 15 | 32922380442828 |
| 16 | 443493622670313 |
| 17 | 6031353319151961 |
| 18 | 82725531355436886 |
| 19 | 1143385727109903585 |
| 20 | 15913217995801644870 |
| 21 | 222875331740976566070 |