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) |
|---|---|
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 60 |
| 6 | 300 |
| 7 | 2100 |
| 8 | 21000 |
| 9 | 252000 |
| 10 | 4284000 |
| 11 | 94248000 |
| 12 | 2733192000 |
| 13 | 106594488000 |
| 14 | 5436318888000 |
| 15 | 369669684384000 |
| 16 | 33270271594560000 |
| 17 | 3959162319752640000 |
| 18 | 625547646520917120000 |
| 19 | 130739458122871678080000 |
| 20 | 36214829900035454828160000 |