# Icosikaiheptagonal Number

Given a number N, the task is to find Nth icosikaiheptagonal number.

An icosikaiheptagonal number is a class of figurate numbers. It has 27 – sided polygon called icosikaiheptagon. The N-th icosikaiheptagonal number count’s the 27 number of dots and all other dots are surrounding with a common sharing corner and make a pattern. The first few icosikaiheptagonol numbers are 1, 27, 78, 154 …

Examples:

Input: N = 2
Output: 27
Explanation:
The second icosikaiheptagonol number is 27.

Input: N = 3
Output: 78

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The N-th icosikaiheptagonal number is given by the formula:

• Nth term of s sided polygon = • Therefore Nth term of 27 sided polygon is Below is the implementation of the above approach:

## C++

 // C++ program to find N-th  // icosikaiheptagonal number  #include     using namespace std;  // Function to find the nth  // icosikaiheptagonal Number  int icosikaiheptagonalNum(int n)  {      return (25 * n * n - 23 * n) / 2;  }     // Driver code  int main()  {      int n = 3;         cout << "3rd icosikaiheptagonal Number is "          << icosikaiheptagonalNum(n);         return 0;  }

## Java

 // Java program to find N-th   // icosikaiheptagonal number   class GFG{      // Function to find the nth   // icosikaiheptagonal number   static int icosikaiheptagonalNum(int n)   {       return (25 * n * n - 23 * n) / 2;   }      // Driver code   public static void main(String[] args)   {       int n = 3;       System.out.print("3rd icosikaiheptagonal Number is " +                                   icosikaiheptagonalNum(n));   }   }      // This code is contributed by shubham

## Python3

 # Python3 program to find N-th  # icosikaiheptagonal number     # Function to find the nth  # icosikaiheptagonal Number  def icosikaiheptagonalNum(n):         return (25 * n * n - 23 * n) // 2;     # Driver code  n = 3;  print("3rd icosikaiheptagonal Number is ",                   icosikaiheptagonalNum(n));     # This code is contributed by Code_Mech

## C#

 // C# program to find N-th   // icosikaiheptagonal number   using System;     class GFG{      // Function to find the nth   // icosikaiheptagonal number   static int icosikaiheptagonal(int n)   {       return (25 * n * n - 23 * n) / 2;   }      // Driver code   public static void Main(String[] args)  {      int n = 3;              Console.Write("3rd icosikaiheptagonal Number is " +                                   icosikaiheptagonal(n));   }   }      // This code is contributed by shivanisinghss2110

Output:

3rd icosikaiheptagonal Number is 78


Reference: http://www.2dcurves.com/line/linep.html

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