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 | 6 |
| 3 | 52 |
| 4 | 428 |
| 5 | 3552 |
| 6 | 29790 |
| 7 | 251980 |
| 8 | 2145822 |
| 9 | 18373296 |
| 10 | 158025186 |
| 11 | 1364247180 |
| 12 | 11815188000 |
| 13 | 102606325136 |
| 14 | 893175905778 |
| 15 | 7791151047204 |
| 16 | 68086757974300 |
| 17 | 595980599148672 |
| 18 | 5224392846601730 |
| 19 | 45857525238248604 |
| 20 | 402997448078904948 |
| 21 | 3545390129177031520 |
| 22 | 31221592914677352138 |