(**) Determine the prime factors of a given positive integer.
Construct a list containing the prime factors and their multiplicity.
prime_factors_mult n = map swap $ encode $ primeFactors n where swap (x,y) = (y,x)
using primeFactors from problem 35 to generate the list of prime factors in ascending order, and encode from problem 10 to compress this list to a list of numbers paired with their multiplicity.
Without relying on encode from problem 10, but using group from Data.List:
prime_factors_mult = map encode . group . primeFactors where encode xs = (head xs, length xs)