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 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 18 |
| 6 | 86 |
| 7 | 549 |
| 8 | 4647 |
| 9 | 52060 |
| 10 | 772976 |
| 11 | 15240116 |
| 12 | 400345371 |
| 13 | 14063594530 |
| 14 | 663256392496 |
| 15 | 42161077371566 |
| 16 | 3625838175218123 |
| 17 | 423372648479289300 |
| 18 | 67333725775723184308 |
| 19 | 14628921614102655999804 |
| 20 | 4352732830667872529962044 |