Split and then add both sides of an array together

def divide_list(numbers):
    half = len(numbers) // 2
    return numbers[:half], numbers[half:]

def add_lists(list_a, list_b):
    if len(list_a) < len(list_b):
        list_a.insert(0,0)
        
    results = []
    for i in range(len(list_a)):
        results.append(list_a[i] + list_b[i])
    
    return results

def split_and_add(numbers, n):
    if len(numbers) == 1:
        return numbers
        
    for i in range(n):
        a,b = divide_list(numbers)
        numbers = add_lists(a,b)
        
    return numbers