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) |
|---|---|
| 3 | 1 |
| 4 | 9 |
| 5 | 62 |
| 6 | 320 |
| 7 | 1837 |
| 8 | 8376 |
| 9 | 45666 |
| 10 | 198471 |
| 11 | 1065418 |
| 12 | 4523403 |
| 13 | 24247545 |
| 14 | 101589616 |
| 15 | 547233490 |
| 16 | 2273356598 |
| 17 | 12341618508 |
| 18 | 50963502172 |
| 19 | 279167141052 |
| 20 | 1147495086055 |
| 21 | 6344204700832 |
| 22 | 25979651242434 |
| 23 | 144938080884808 |
| 24 | 591635283209270 |
| 25 | 3328970814605391 |
| 26 | 13551109648829458 |
| 27 | 76853618775913752 |