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 | 480 |
| 6 | 1440 |
| 7 | 30240 |
| 8 | 161280 |
| 9 | 2177280 |
| 10 | 14515200 |
| 11 | 399168000 |
| 12 | 1916006400 |
| 13 | 74724249600 |
| 14 | 523069747200 |
| 15 | 10461394944000 |
| 16 | 167382319104000 |
| 17 | 5690998849536000 |
| 18 | 38414242234368000 |
| 19 | 2189611807358976000 |
| 20 | 19463216065413120000 |
| 21 | 613091306060513280000 |