Math & Numbers

Python Program for Fibonacci Series

The Fibonacci sequence is a series where each number is the sum of the two preceding ones, starting from 0 and 1. Here we implement iterative generation and generator streaming.

Python Source Code

Editable code sample with line numbers

Python

Expected Output

When this program is compiled and executed, the terminal outputs:

First 10 Fibonacci numbers:
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

The 15th Fibonacci number is: 610

How the Code Works

The iterative Fibonacci generator stores computed values in a list by repeatedly adding the last two elements. To compute single values without storing intermediate sequences, nth_fibonacci uses two accumulator variables (a, b) and updates them simultaneously via tuple unpacking, requiring only O(1) auxiliary memory.

Time Complexity

O(N)

Space Complexity

O(1) for scalar calculation, O(N) to store list

Key Takeaways & Best Practices

Iterative calculation avoids recursion depth limits and call stack overhead in Python.
Tuple unpacking (a, b = b, a + b) eliminates the need for temporary swap variables.

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