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 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 15 |
| 4 | 60 |
| 5 | 260 |
| 6 | 1820 |
| 7 | 12376 |
| 8 | 136136 |
| 9 | 1514513 |
| 10 | 27261234 |
| 11 | 488605194 |
| 12 | 14169550626 |
| 13 | 411591708660 |
| 14 | 19344810307020 |
| 15 | 908637119420910 |
| 16 | 69056421075989160 |
| 17 | 5249543573067466872 |
| 18 | 645693859487298425256 |
| 19 | 79413089729752455762384 |
| 20 | 15803204856220738696714416 |