main_inf_restart.py

#Variables

number = 1 # initial positive number
iterations = 0 # to count iteration 
List_iteration= [0] # lists to plot
List_number= [0]
## main_num.txt is a file of all numbers (num) encountered during loops, this allows to skip ahead if a loop reaches a previously terminating string.
## main_seq.txt contains all numbers with iterations larger than 0, i.e. numbers who haven't already been encountered previously.

#Interaction
print('\n Do you want to start from a specific number [y/n] ?')
option_number=str(input(' default is 1, enter y or n to continue : '))

if (option_number == ['Y', 'y']):
    number =int(input(' Enter the number : '))
try:
    import os
    with open("main_seq.txt", "rb") as file:
        try:
            file.seek(-2, os.SEEK_END)
            while file.read(1) != b'\n':
                file.seek(-2, os.SEEK_CUR)
        except OSError:
            file.seek(0)
        last_line = file.readline().decode()
        placeKeeper = last_line.find(' ')
        number = last_line[0:placeKeeper]
        number = (int(number) + 1)
    print(f"We'll be continuing with {number}!")
except Exception:
    print("We'll be starting with 1!")
    number = 1
    

print('\n Press Ctrl + C any time to quit \n')
start=str(input(' Press Enter to begin ! \n'))

num = number  


while True:
    f = open("main_num.txt", "r+") # Opens ClltzSet.txt for reading
    fileSet = f.read().splitlines()
         
    if (str(num) in fileSet):  
        if iterations != 0:
            f.close()   # Closes main_num.txt
            print(' Number : ',number, ', Iterations : ',iterations, ', True ', '\n' ) # Adds the number, iterations, and sequence to the file if the iterations are not 0.
            f = open("main_seq.txt", "a")
            f.write(f"{number} : {iterations} {List_number}\n")
            f.close()
        number += 1 #increment
        iterations=0
        num = number

        List_iteration=[0] # reset/empty lists for next round
        List_number=[0]
         
    elif(num%2) == 0:  #if number is even make it odd
        f.write(f"{num}\n")    # Writes the variable to the set
        num = int(num/2)
        iterations += 1 #increment

        List_number.append(num) # Add number/value in list, every time
        List_iteration.append(iterations) # Add iteration value/increment

    else: 
        f.write(f"{num}\n")    # Writes the variable to the set
        num = int(num*3+1)  #if number is odd make it even
        iterations += 1

        List_number.append(num) # Add number value in list, every time
        List_iteration.append(iterations) #iteration
 
    if(num == 1): #Next number !
        f.close()   # Closes the file

        f = open("main_seq.txt", "a")
        f.write(f"{number} : {iterations} {List_number}\n")
        f.close()
        
        print(' Number : ',number, ', Iterations : ',iterations, ', True ', '\n' )
        number += 1 #increment
        iterations=0
        num = number

        List_iteration=[0] # reset/empty lists for next round
        List_number=[0]
        
    elif(num == 0): # conjecture break , alert !
        print(' Number : ', number, ', False ', '\n' )
        break #exit loop