# Program to calculate the sum of even numbers in a range

# Get input from the user
n = int(input("Enter a number: "))

# Initialize a variable to store the sum
sum = 0

# Iterate through the range of numbers from 1 to n
for i in range(1, n+1):
# Check if the current number is even
if i % 2 == 0:
# If it is even, add it to the sum
sum += i

# Print the sum
print("The sum of even numbers from 1 to", n, "is", sum)

2.

# Program to calculate the sum of odd numbers in a range

# Get input from the user
n = int(input("Enter a number: "))

# Initialize a variable to store the sum
sum = 0

# Iterate through the range of numbers from 1 to n
for i in range(1, n+1):
# Check if the current number is odd
if i % 2 == 1:
# If it is odd, add it to the sum
sum += i

# Print the sum
print("The sum of odd numbers from 1 to", n, "is", sum)

3.

# Program to calculate the sum of the series S = 1 + 1/2 + 1/3 + ... + 1/n

# Get input from the user
n = int(input("Enter a number: "))

# Initialize a variable to store the sum
sum = 0

# Iterate through the range of numbers from 1 to n
for i in range(1, n+1):
# Add the current term to the sum
sum += 1 / i

# Print the sum
print("The sum of the series S = 1 + 1/2 + 1/3 + ... + 1/n for n =", n, "is", sum)