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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 708 |
| 7 | 4914 |
| 8 | 38982 |
| 9 | 347884 |
| 10 | 3449552 |
| 11 | 37625605 |
| 12 | 447705880 |
| 13 | 5771174672 |
| 14 | 80116195690 |
| 15 | 1191625115214 |
| 16 | 18905479581944 |
| 17 | 318687249924106 |
| 18 | 5688074315975376 |
| 19 | 107163510318836508 |
| 20 | 2125225387203526220 |
| 21 | 44253982345638143492 |
| 22 | 965390692549001250560 |