Skip to content
Related Articles

Related Articles

Improve Article

Find the sum of the first N Centered Octadecagonal Numbers

  • Last Updated : 18 Mar, 2021

Given a number N, the task is to find the sum of first N Centered Octadecagonal numbers.
Examples: 
 

Input: N = 3 
Output: 75 
Explanation: 
1, 19 and 55 are the first three centered octadecagonal numbers.
Input: N = 10 
Output: 298 
 

 

Approach: 
 

  1. Initially, we need to create a function which will help us to calculate the Nth centered octadecagonal number.
  2. Now, run a loop starting from 1 to N, to find ith centered octadecagonal numbers.
  3. Add all the above calculated centered octadecagonal numbers.
  4. Finally, display the sum of the first N centered octadecagonal numbers.

Below is the implementation of the above approach: 
 



C++




// C++ program to find the sum of the
// first N centered octadecagonal numbers
#include<bits/stdc++.h>
using namespace std;
 
// Function to find the N-th centered
// octadecagonal number
int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
        summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
int main()
{
    int n = 3;
 
    cout << (sum_center_octadecagon_num(n));
    return 0;
}
 
// This code is contributed by Rajput-Ji

Java




// Java program to find the sum of the 
// first N centered octadecagonal numbers
class GFG {
     
// Function to find the N-th centered
// octadecagonal number
static int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
static int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
       summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
public static void main(String[] args)
{
    int n = 3;
 
    System.out.println(sum_center_octadecagon_num(n));
}
}
 
// This code is contributed by sapnasingh4991

Python3




# Python3 program to find the sum of
# the first N Centered Octadecagonal
# numbers
 
# Function to find the N-th
# Centered octadecagonal
# number
def center_octadecagon_num(n):
 
    # Formula to calculate 
    # nth centered octadecagonal
    # number
    return (9 * n * n - 9 * n + 1)
     
   
# Function to find the sum of
# the first N Centered
# octadecagonal numbers
def sum_center_octadecagon_num(n) :
     
    # Variable to store
    # the sum
    summ = 0
     
    # Iterating through the range
    # 1 to N
    for i in range(1, n + 1):
 
        summ += center_octadecagon_num(i)
     
    return summ
   
# Driver code
if __name__ == '__main__' :
           
    n = 3
     
    print(sum_center_octadecagon_num(n))

C#




// C# program to find the sum of the
// first N centered octadecagonal numbers
using System;
 
class GFG {
     
// Function to find the N-th centered
// octadecagonal number
static int center_octadecagon_num(int n)
{
 
    // Formula to calculate
    // nth centered octadecagonal
    // number
    return (9 * n * n - 9 * n + 1);
}
 
// Function to find the sum of the first
// N centered octadecagonal numbers
static int sum_center_octadecagon_num(int n)
{
 
    // Variable to store
    // the sum
    int summ = 0;
 
    // Iterating through the range
    // 1 to N
    for(int i = 1; i < n + 1; i++)
    {
        summ += center_octadecagon_num(i);
    }
    return summ;
}
 
// Driver Code
public static void Main(String[] args)
{
    int n = 3;
 
    Console.WriteLine(sum_center_octadecagon_num(n));
}
}
 
// This code is contributed by sapnasingh4991

Javascript




<script>
    // Javascript program to find the sum of the 
    // first N centered octadecagonal numbers
     
    // Function to find the N-th centered
    // octadecagonal number
    function center_octadecagon_num(n)
    {
 
        // Formula to calculate
        // nth centered octadecagonal
        // number
        return (9 * n * n - 9 * n + 1);
    }
 
    // Function to find the sum of the first
    // N centered octadecagonal numbers
    function sum_center_octadecagon_num(n)
    {
 
        // Variable to store
        // the sum
        let summ = 0;
 
        // Iterating through the range
        // 1 to N
        for(let i = 1; i < n + 1; i++)
        {
            summ += center_octadecagon_num(i);
        }
        return summ;
    }
     
    let n = 3;
    document.write(sum_center_octadecagon_num(n));
 
// This code is contributed by divyeshrabadiya07.
</script>
Output: 
75

 

Time Complexity: O(N).
 

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.




My Personal Notes arrow_drop_up
Recommended Articles
Page :