How to make it so that it takes elements from the list in a loop?

Question

Python

The question is insanely simple, but I don't have the knowledge to do what I'm asking.
ESSENCE OF THE QUESTION: There is a list, it has 25 elements. I need to have a cycle that will take 1,2,3 elements and divide them by 3. For example, it takes 1,2,3 and divides them by 3, then 2,3, 4 and again divides by three; 3, 4, 5 and again on the 3rd division. 4, 5, 6 and again by 3 division, so all 25 elements

Answer 1

mylist = list(range(1, 26))  # Делаем массив с элементами от 1 до 25
m = []  # Делаем пустой массив куда будем заносить результаты

for n in range(23):
    sum_ = mylist[n] + mylist[n + 1] + mylist[n + 2]  # Сумма 3 подряд идущих элементов от n
    m.append(sum_ / 3)  # Добавление результата

print(m)