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) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 72 |
| 3 | 48 |
| 4 | 21600 |
| 5 | 540 |
| 6 | 2540160 |
| 7 | 483840 |
| 8 | 36288000 |
| 9 | 896000 |
| 10 | 31614105600 |
| 11 | 1149603840 |
| 12 | 7139902049280000 |
| 13 | 2196892938240000 |
| 14 | 941525544960000 |
| 15 | 15216574464000 |
| 16 | 16326052949606400000 |
| 17 | 443241256550400000 |
| 18 | 11991344662654156800000 |
| 19 | 1100420292929126400000 |