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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 15 |
| 7 | 105 |
| 8 | 735 |
| 9 | 4095 |
| 10 | 26775 |
| 11 | 162855 |
| 12 | 1105335 |
| 13 | 7187895 |
| 14 | 51126075 |
| 15 | 356831475 |
| 16 | 2676468795 |
| 17 | 19890931515 |
| 18 | 156769986555 |
| 19 | 1232704469115 |
| 20 | 10178240218875 |
| 21 | 84190426730235 |
| 22 | 725667326178795 |