The goal is to enumerate the powers of 3, 5, and 7, once each. Since power sequences all overlap at x^0 = 1, but we specifically don't want to enumerate 1 three times, we have to give one (or, from an alternative viewpoint, two) of the variables special treatment. Whether you name the variables "three", "five", and "seven", or "next_power_of_three", "next_power_of_five", and "next_power_of_seven", you're doing something strange by starting one of them at 1 and the other two past 1, and that should be commented on. The naming-only solution "powers_of_three_initialized_starting_at_three_to_the_zeroeth", "powers_of_five_initialized_starting_at_five_to_the_first", and "powers_of_seven_initialized_starting_at_seven_to_the_first", is hilariously awful, and still requires a comment to explain why the threes variable is more (or less) special than the other two.