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 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 101 |
| 5 | 756 |
| 6 | 6607 |
| 7 | 65794 |
| 8 | 733833 |
| 9 | 9046648 |
| 10 | 121961051 |
| 11 | 1782690174 |
| 12 | 28055070397 |
| 13 | 472594822324 |
| 14 | 8479144213191 |
| 15 | 161340195463066 |
| 16 | 3243707386310033 |
| 17 | 68679247688467056 |
| 18 | 1526976223741111987 |
| 19 | 35557878951515668726 |
| 20 | 865217354118762606021 |