Plzz explain this algo

Question

sum += pow(2*i, 2);

Answer 1

input is 3 and output 56 explain

Answer 2

2*2+ 4*4+6*6= 56 ....

Answer 3

Happy to help explains well.
just by that line of code, I was not able to guess it was in a loop;; is it possible to share the whole code, or is that the only thing that was given?