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 | 5 |
| 3 | 32 |
| 4 | 198 |
| 5 | 1584 |
| 6 | 12480 |
| 7 | 122520 |
| 8 | 1214640 |
| 9 | 14011200 |
| 10 | 166924800 |
| 11 | 2274894720 |
| 12 | 31135104000 |
| 13 | 485667705600 |
| 14 | 7710089587200 |
| 15 | 133974352512000 |
| 16 | 2386854434764800 |
| 17 | 46621903994265600 |
| 18 | 918384939343872000 |
| 19 | 19760215067873280000 |
| 20 | 430137075045629952000 |
| 21 | 10042411264251125760000 |