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) |
|---|---|
| 3 | 2 |
| 4 | 6 |
| 5 | 36 |
| 6 | 144 |
| 7 | 4320 |
| 8 | 64800 |
| 9 | 777600 |
| 10 | 65318400 |
| 11 | 2743372800 |
| 12 | 109734912000 |
| 13 | 29628426240000 |
| 14 | 3199870033920000 |
| 15 | 383984404070400000 |
| 16 | 12671485334323200000 |
| 17 | 29271131122286592000000 |
| 18 | 49175500285441474560000000 |
| 19 | 3835689022264435015680000000 |
| 20 | 1196734974946503724892160000000 |