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 | 1 |
| 3 | 7 |
| 4 | 27 |
| 5 | 121 |
| 6 | 553 |
| 7 | 3865 |
| 8 | 24625 |
| 9 | 202954 |
| 10 | 1519540 |
| 11 | 14193455 |
| 12 | 132441998 |
| 13 | 1381539355 |
| 14 | 14096067555 |
| 15 | 168745220585 |
| 16 | 1961128020387 |
| 17 | 25473872598375 |
| 18 | 324797436024684 |
| 19 | 4647784901400988 |
| 20 | 65394584337577858 |
| 21 | 1012005650484163962 |
| 22 | 15285115573675197704 |