Which function describes the sequence 3, 6, 12, 24, … for n = 1, 2, 3, …?

A. f(n) = 3n

B. f(n) = 2^n + 1

C. f(n) = 3 ∙ 2^n-1

D. f(n) = (n - 1)^2 + 3