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) |
|---|---|
| 4 | 6 |
| 5 | 30 |
| 6 | 300 |
| 7 | 2100 |
| 8 | 21840 |
| 9 | 236880 |
| 10 | 2731680 |
| 11 | 30048480 |
| 12 | 400498560 |
| 13 | 5206481280 |
| 14 | 79117758720 |
| 15 | 1273944672000 |
| 16 | 21690789120000 |
| 17 | 368743415040000 |
| 18 | 6993068898816000 |
| 19 | 132868309077504000 |
| 20 | 2779011281958912000 |
| 21 | 60792138929313792000 |
| 22 | 1388517998616612864000 |