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 | 1 |
| 2 | 6 |
| 3 | 36 |
| 4 | 180 |
| 5 | 1260 |
| 6 | 7560 |
| 7 | 45360 |
| 8 | 83160 |
| 9 | 498960 |
| 10 | 1081080 |
| 11 | 6486480 |
| 12 | 32432400 |
| 13 | 110270160 |
| 14 | 551350800 |
| 15 | 2095133040 |
| 16 | 10475665200 |
| 17 | 73329656400 |
| 18 | 240940299600 |
| 19 | 1686582097200 |
| 20 | 48910880818800 |
| 21 | 1516237305382800 |