Compute a range python

Question

I'm stuck on a range. It should be pretty simple by for some reason I can't figure it out. So i have a range of (x,y) and it should add every number within that range however once it gets to the third it should double and then continue adding them.

start = int(input())
end = int(input())
sum = 0
a = range (start,end)
for i in range (start,end):
        sum = sum + i
        i +=  1

Answer 1

start = int(input())
end = int(input())
sum = 0
for i, v in enumerate(range(start,end+1)): #7+1 as it's non inclusive
    sum+=v
    if (i+1)%3 == 0: #every 3 it *2
         sum *=2
print(sum)

and it outputs 72, as expected

Answer 2

Iterate over the range with step=3, and within that loop add the sum of each smaller range to the total before multiplying it by two.

total, start, end = 0, int(input()), int(input()) + 1
for i in range(start, end, 3):
    total += sum(range(i, min(i+3, end)))
    total *= 2
print(total)

2
7
72