Q.Take a look at the series below:
1, 1, 2, 3, 5, 8, 13, 21, 34, 55…
To form the pattern, start by writing 1 and 1. Add them together to get 2. Add the last two numbers: 1+2 = 3.Continue adding the previous two numbers to find the next number in the series. These numbers make up the famed Fibonacci sequence: previous two numbers are added to get the immediate new number.

Each Fibonacci term is the sum of the previous two; a function with two "sliding" variables generates the series.

def fibonacci(n):
    a, b = 1, 1                 # the first two terms
    for term in range(n):
        print(a, end=" ")
        a, b = b, a + b         # slide the pair forward

num = int(input("How many terms? "))
fibonacci(num)

Sample run (input 10):

How many terms? 10
1 1 2 3 5 8 13 21 34 55
``` …

The idea. The passage defines the series by a recurrence: every term is the sum of its two predecessors. To generate it you never need the whole list — only the last two values. Two variables plus Python's simultaneous assignment (a, b = b, a + b) implement the rule directly, wrapped in a user-defined function so the caller chooses how many terms.

def fibonacci(n):
    # Print the first n terms of the Fibonacci sequence
    a, b = 1, 1                  # the two starting terms from the passage
    for term in range(n):
        print(a, end=" ")
        a, b = b, a + b          # previous two numbers -> the new number
    print()

num = int(input("How many terms? "))
fibonacci(num)

Sample run (user asks for 10 terms)

How many terms? 10
1 1 2 3 5 8 13 21 34 55

This matches the series in the question exactly: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55.

Dry run of the first six passes

Why the simultaneous assignment matters

• a, b = b, a + b evaluates the whole right side first, then assigns — both updates use the old values. …