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 | 840 |
| 2 | 5040 |
| 3 | 11880 |
| 4 | 175560 |
| 5 | 570024 |
| 6 | 5997600 |
| 7 | 34234200 |
| 8 | 70073640 |
| 9 | 569729160 |
| 10 | 1262451960 |
| 11 | 6643717080 |
| 12 | 6927399360 |
| 13 | 59312218680 |
| 14 | 657557188200 |
| 15 | 1288881113520 |
| 16 | 7994422608480 |
| 17 | 9803968814640 |
| 18 | 73148660184600 |
| 19 | 130903460103024 |
| 20 | 250036769127600 |
| 21 | 1081389616791120 |