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 | 4916 |
| 8 | 39008 |
| 9 | 348202 |
| 10 | 3453572 |
| 11 | 37679044 |
| 12 | 448455648 |
| 13 | 5782307134 |
| 14 | 80291122976 |
| 15 | 1194530208634 |
| 16 | 18956382485568 |
| 17 | 319626461800751 |
| 18 | 5706286536509228 |
| 19 | 107533930423507736 |
| 20 | 2133112981295131824 |
| 21 | 44429507242283663790 |
| 22 | 969465861672912148324 |