Beginner's Python – Computing a sum

I’m trying to compute \sum_{k=1}^{M} = \frac{1}{(2k)^2}

s = 0
M = 3
k = 1

for i in range(M):
    s = 1/(2*k)**2
    k += 1
    print(s)

Terminal outputs

0.25
0.0625
0.027777777777777776

Where as I should be getting

0.340277777778

Which is the sum of the series from k = 1 M = 3, since I am pretty sure the task is not asking me to compute k = 1, 2, 3 separately like above.

>Solution :

You are assigning a new value to s every loop.

s = 0
M = 3
k = 1

for i in range(M):
    s += 1/(2*k)**2
    k += 1
    print(s)

Output: 0.3402777777777778