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 | 347898 |
| 10 | 3449832 |
| 11 | 37630215 |
| 12 | 447778848 |
| 13 | 5772349056 |
| 14 | 80135742750 |
| 15 | 1191964110777 |
| 16 | 18911623686552 |
| 17 | 318803730114225 |
| 18 | 5690383738630956 |
| 19 | 107211361385886516 |
| 20 | 2126260453008788598 |
| 21 | 44277328711513910475 |
| 22 | 965939103520765611768 |