Adding to a starting value in a list each time for loop runs?

I'm trying to add value z to starting value x each time the following for loop runs. The output I'm expecting is 1000,1021,1042,1063... or x, x+z, x+z+z, x+z+z+z...

When I run the following, I only get 1000,1021 as the output.

Why am I only getting a list of two values when the range is 0-1000? I'm obviously very new to python, so I'm sure the answer is something simple that I haven't come across yet.

Thanks for your time!

x = [1000]
y = []
z = 21
for i in range(0,1000):
    y = np.append(x,sum(x,z))
print(y)

Solution

The code in your query is independent of the loop variable i, the loop is running for 1000 times but it does not do anything.

Before the loop exits, it adds two elements to y i.e. x and sum(x,z), which are 1000 and 1021, hence you get the output [1000 1021]

You can try the below code to increment every time by z using range() function

for i in range(1000, 1100, z):
    y.append(i)
print(y)
#Output: 1000, 1021, 1042, 1063, 1084