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 | 1 |
| 2 | 6 |
| 3 | 40 |
| 4 | 300 |
| 5 | 2475 |
| 6 | 22022 |
| 7 | 208208 |
| 8 | 2068560 |
| 9 | 21414900 |
| 10 | 229523800 |
| 11 | 2533942752 |
| 12 | 28698821320 |
| 13 | 332357673375 |
| 14 | 3925129083750 |
| 15 | 47167131780000 |
| 16 | 575637606165600 |
| 17 | 7123515376299300 |
| 18 | 89266155250239000 |
| 19 | 1131410294476020000 |
| 20 | 14489559984061890000 |
| 21 | 187330691180608155180 |
| 22 | 2443121585638964379864 |