n1 = 1
n2 = 1
n3 = n1 + n2
for i in range(10):n1 + n2print(n3)n1 = n2n2 = n3

According to what I know, this should be the simplest way of outputting the first 10 digits of the series, however, it prints 2 10 times. I don't understand why n1 doesn't get set to n2, and n2 doesn't get set to n3 after n3 has been printed.

There are many issues with your code. And you should first learn and try as much as you can on your own. I am also a beginner so I know what you are thinking. For some quick edits to make it workable:

n1 = 0
n2 = 1
n3 = 0
for i in range(10):n3 = n1 + n3print(n3)n1 = n2n2 = n3

1. The series starts with 0, you initialized it with 1.
2. The update statement n3=n1+n2 is outside the loop, how will it update? What is happening here is n3 = 1 + 1 = 2 in your code stays the same and it doesn't change.