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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 21 |
| 6 | 176 |
| 7 | 1893 |
| 8 | 25030 |
| 9 | 382272 |
| 10 | 6604535 |
| 11 | 127222636 |
| 12 | 2702798537 |
| 13 | 62778105236 |
| 14 | 1582725739329 |
| 15 | 43046433007765 |
| 16 | 1256332883208474 |
| 17 | 39165907107963273 |
| 18 | 1298945495674093932 |
| 19 | 45666536827274985585 |
| 20 | 1696460750775267473762 |