Logic Building
def sum_even(n):
# Base case
if n == 0:
return 0
# Recursive case
# nth even number is 2*n
return (2 * n) + sum_even(n - 1)
# Test
n = int(input("Enter n: "))
result = sum_even(n)
print(f"Sum of first {n} even numbers: {result}")Output
Enter n: 5 Sum of first 5 even numbers: 30
Nth even number is 2*n.
Key Concepts:
- Base case: sum(0) = 0
- Nth even number = 2*n
- Add current even number to sum of previous