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 | 34 |
| 3 | 378 |
| 4 | 3186 |
| 5 | 25620 |
| 6 | 214410 |
| 7 | 1930080 |
| 8 | 18881250 |
| 9 | 200907060 |
| 10 | 2318843370 |
| 11 | 28914797640 |
| 12 | 387867845250 |
| 13 | 5573855579340 |
| 14 | 85476008430090 |
| 15 | 1393770581296320 |
| 16 | 24086416578328290 |
| 17 | 439832565550644900 |
| 18 | 8463528886854858090 |
| 19 | 171191360282164168440 |
| 20 | 3631513434281720800770 |