Given a number n, the task is to find the nth Enneadecagonal number.
An Enneadecagonal number is a nineteen-sided polygon in mathematics. It belongs to a class of figurative number. The number contains the number of dots and the dots are arranged in a pattern or series. An Enneadecagonal number is also known as nonadecagon. The dots have common points and all other dots are arrange in the successive layer.

Examples :

Input : 4
Output :106

Input :10
Output :775 Formula to find nth Enneadecagonal number : ## C++

 // C++ program to find  // nth Enneadecagonal number  #include  using namespace std;     // Function to calculate   // Enneadecagonal number  int nthEnneadecagonal(long int n)  {      // Formula for finding      // nth Enneadecagonal number      return (17 * n * n - 15 * n) / 2;  }     // Drivers code  int main()  {      long int n = 6;      cout << n << "th Enneadecagonal number :" << nthEnneadecagonal(n);      return 0;  }

## Java

 // Java program to find  // nth Enneadecagonal number  import java.io.*;     class GFG {         // Function to calculate       // Enneadecagonal number      static int nthEnneadecagonal(int n)      {                     // Formula for finding          // nth Enneadecagonal number          return (17 * n * n - 15 * n) / 2;      }             // Driver Code      public static void main (String[] args)      {                     int n = 6;          System.out.print(n + "th Enneadecagonal number :");                 System.out.println( nthEnneadecagonal(n));      }  }     // This code is contributed by m_kit.

## Python3

 # Program to find nth  # Enneadecagonal number     def nthEnneadecagonal(n) :             # Formula to calculate nth      # Enneadecagonal number      return (17 * n * n - 15 * n) // 2    # Driver Code  if __name__ == '__main__' :                 n = 6     print(n,"th Enneadecagonal number :"                 , nthEnneadecagonal(n))     # This code is contributed  by Ajit

## C#

 // C# program to find  // nth Enneadecagonal number  using System;     class GFG  {      // Function to calculate       // Enneadecagonal number      static int nthEnneadecagonal(int n)      {                 // Formula for finding      // nth Enneadecagonal number      return (17 * n * n - 15 * n) / 2;      }             // Driver Code      static public void Main ()      {      int n = 6;      Console.Write(n + "th Enneadecagonal number :");             Console.WriteLine( nthEnneadecagonal(n));      }  }     // This code is contributed by aj_36

## PHP

 

Output :

6th Enneadecagonal number :261


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Improved By : jit_t