how to write an algorithm that generates DNA sequences without tandem repeats? (python) [duplicate]

I need to write an algorithm that generates random DNA sequences, without tandem repeats, but I don't know how to make the computer recognize these tandem repeats. Can anyone help me?

This is what I have so far, but it only deletes tandem repeats of length 2 (ex: CGATT ==> CGATA)

from random import randint

def generate_DNA(n):                      
                                  
    alphabet = ['A','C','T','G']          
    seq = []

    while len(seq) < n:   
                  
        j = alphabet[randint(0,3)]    
        seq.append(j)
        for i in range(1,len(seq)):       
            if seq[i] == seq[i-1]:
                del seq[i]

    return seq

print(generate_DNA(10))