# Python Data Structures and Algorithms - Recursion: Sum of n+(n-2)+(n-4)...

## Python Recursion : Exercise-7 with Solution

Write a Python program to calculate the sum of the positive integers of n+(n-2)+(n-4)... (until n-x =< 0) using recursion.

**Sample Solution**:

**Python Code:**

```
# Define a function named sum_series that calculates the sum of a series of numbers
def sum_series(n):
# Check if 'n' is less than 1 (base case for the series)
if n < 1:
# If 'n' is less than 1, return 0 (base case value for the sum)
return 0
else:
# If 'n' is greater than or equal to 1, calculate the sum of 'n' and
# recursively call the sum_series function with 'n - 2'
return n + sum_series(n - 2)
# Print the result of calling the sum_series function with the input value 6
print(sum_series(6))
# Print the result of calling the sum_series function with the input value 10
print(sum_series(10))
```

Sample Output:

12 30

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