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) |
|---|---|
| 2 | 12 |
| 3 | 126 |
| 4 | 1176 |
| 5 | 10290 |
| 6 | 86436 |
| 7 | 705894 |
| 8 | 5647152 |
| 9 | 44471322 |
| 10 | 345888060 |
| 11 | 2663338062 |
| 12 | 20338217928 |
| 13 | 154231485954 |
| 14 | 1162668124884 |
| 15 | 8720010936630 |
| 16 | 65109414993504 |
| 17 | 484251274014186 |
| 18 | 3589156501516908 |
| 19 | 26519878594541598 |
| 20 | 195409631749253880 |