How to go from 2*4*6 (2n) to (2^n)n

[mathbrah]

how would one see the first

and come up with the second

 

[SteamKing]

Have you tried factoring 2 from 2*4*6*...(2n)?

 

[Mark44]

In the product 2 * 4 * 6 * ... * (2n), how many factors are explicitly shown there?

 

[vanhees71]

I write it even a bit more explicitly
$$2 \cdot 4 \cdot 6 \cdots (2n)=(2 \cdot 1) \cdot (2 \cdot 2) \cdot (2 \cdot 3) \cdots (2n).$$