CollatzConjecture.py

print("type x to quit")
b = input("up to what number: ")
while b != "x":
    li = []#list that stores the numbers produced
    List = []#list that contains all lists
    for i in range(2,int(b)):
        li.append(i)
        while i != 1:
            if i % 2 == 0: #even
                i = i/2
                li.append(i)
            else:
                i = 3*i+1 #odd
                li.append(i)
        List.append(li)
        li = []
    print(max(List,key=len)) #prints the longest list, out of all lists
    print(len(max(List,key=len)))#prints the length of the list
    b = input("up to what number: ")

#the first number is the number that produced the list
#hi Mr.Robertson


# resource - https://stackoverflow.com/questions/13400876/python-length-of-longest-sublist