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 | 2 |
| 3 | 12 |
| 4 | 48 |
| 5 | 144 |
| 6 | 1440 |
| 7 | 34560 |
| 8 | 483840 |
| 9 | 7257600 |
| 10 | 58060800 |
| 11 | 3135283200 |
| 12 | 125411328000 |
| 13 | 2633637888000 |
| 14 | 57940033536000 |
| 15 | 5562243219456000 |
| 16 | 27811216097280000 |
| 17 | 723091618529280000 |
| 18 | 6507824566763520000 |
| 19 | 364438175738757120000 |
| 20 | 327994358164881408000000 |