count = 1, pNum = 2, sum = 0
factor = 1, sum = 0
count = 2, pNum = 3, sum = 0
factor = 1, sum = 0
factor = 2, sum = 1
count = 3, pNum = 4, sum = 0
factor = 1, sum = 0
factor = 2, sum = 1
factor = 3, sum = 3
count = 4, pNum = 5, sum = 0
factor = 1, sum = 0
factor = 2, sum = 1
factor = 3, sum = 1
factor = 4, sum = 1