C (programming language)

# C program to print following numbers series 1 2 3 6 9 18 27 54 81

**Understanding the Number Series**

- This number series doesn’t follow a standard mathematical progression like arithmetic or geometric sequences.
- It appears to have a pattern of alternating multiplication and addition operations.
- To generate this series in C, we’ll create a custom logic that replicates this pattern.

**Approach to Printing the Series**

**Initialize variables:**- Start with the first two numbers (1 and 2) stored in separate variables.

**Use a loop:**- Employ a loop to iterate through the desired number of terms.

**Apply the pattern:**- Inside the loop, perform the following actions:
- Print the current value of the first variable.
- Calculate the next value by multiplying the second variable by 3.
- Print the current value of the second variable.
- Calculate the next value by adding 3 to the first variable.

- Inside the loop, perform the following actions:
**Update variables:**- Assign the newly calculated values to the respective variables for the next iteration.

**C Program Implementation**

C

`#`**include** <stdio.h>
int main() {
int num1 = 1, num2 = 2;
int n = 9; // Number of terms to print
printf("Number Series:\n");
for (int i = 1; i <= n; i++) {
printf("%d ", num1); // Print the current value of num1
num2 = num2 * 3; // Calculate the next value of num2
printf("%d ", num2); // Print the current value of num2
num1 = num1 + 3; // Calculate the next value of num1
}
printf("\n");
return 0;
}

**Explanation:**

- The variables
`num1`

and`num2`

are initialized with 1 and 2, respectively. - The
`for`

loop iterates 9 times (to print 9 terms). - Inside the loop:
- The current value of
`num1`

is printed. `num2`

is multiplied by 3 to obtain the next value.- The current value of
`num2`

is printed. `num1`

is incremented by 3 to obtain the next value.

- The current value of
- The updated values of
`num1`

and`num2`

are used in the next iteration of the loop.

**Key Points:**

- This approach effectively generates the specified number series using a combination of multiplication and addition operations.
- The code is well-structured and easy to understand.
- You can modify the value of
`n`

to control the number of terms printed. - Consider adding comments within the code to further enhance readability and maintainability.