Logic Building/Phase 2 - Level 3: Mathematical & Logical Patterns/Program

Alternating Series Sum

Calculate 1 - 1/2 + 1/3 - 1/4 + ... ± 1/n.

Logic BuildingIntermediate

Logic Building

# Take n
n = int(input("Enter n: "))

# Calculate sum
sum_alt = 0
for i in range(1, n + 1):
    if i % 2 == 1:
        sum_alt += 1 / i
    else:
        sum_alt -= 1 / i

print(f"Sum: {sum_alt:.4f}")

Output

Enter n: 5
Sum: 0.7833

Alternate signs based on position.

Key Concepts:

Add for odd positions
Subtract for even positions
Create alternating pattern

Sum of Harmonic Series