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 | 4 |
| 4 | 27 |
| 5 | 201 |
| 6 | 1730 |
| 7 | 17403 |
| 8 | 200753 |
| 9 | 2607034 |
| 10 | 37614509 |
| 11 | 596935373 |
| 12 | 10334325760 |
| 13 | 193820393781 |
| 14 | 3914731176005 |
| 15 | 84716449797164 |
| 16 | 1955520065429447 |
| 17 | 47960724916860501 |
| 18 | 1245468600257306394 |
| 19 | 34139796085144434199 |
| 20 | 985066290121984334613 |