Given a number n, the task is to find the nth heptadecagonal number .
A heptadecagonal number is class of figurate number. It has seventeen sided polygon called heptadecagon. The n-th heptadecagonal number count’s the seventeen number of dots and all others dots are surrounding with a common sharing corner and make a pattern.

Examples:

Input : 5
Output :155

Input :9
Output :549 Formula to calculate nth heptadecagonal number: ## C++

 // C++ program to find Nth  // heptadecagonal number  #include  using namespace std;     // Function to calculate heptadecagonal  // number  int heptadecagonalNum(long int n)  {      return ((15 * n * n) - 13 * n) / 2;  }     // Driver Code  int main()  {      long int n = 3;      cout << n << "th Heptadecagonal number : ";      cout << heptadecagonalNum(n);      cout << endl;      n = 8;      cout << n << "th Heptadecagonal number : ";      cout << heptadecagonalNum(n);         return 0;  }

## Java

 // Java program to find Nth heptadecagonal number  import java.io.*;     class GFG {             // Function to calculate heptadecagonal      // number      static long heptadecagonalNum(long n)      {          return ((15 * n * n) - 13 * n) / 2;      }             // Driver Code      public static void main (String[] args)      {          long n = 3;          System.out.print( n + "th Heptadecagonal"                                   + " number : ");          System.out.println( heptadecagonalNum(n));                     n = 8;          System.out.print( n + "th Heptadecagonal"                                  + " number : ");          System.out.print( heptadecagonalNum(n));      }  }     // This code is contributed by anuj_67.

## Python3

 # Python program to find Nth  # heptadecagonal number     # Function to calculate  # heptadecagonal number  def heptadecagonalNum(n):         # Formula to calculate nth      # heptadecagonal number      return ((15 * n * n) - 13 * n) // 2       # Driver Code  n = 3 print("%sth Heptadecagonal number : " %n,                      heptadecagonalNum(n))  n = 8 print("%sth Heptadecagonal number: " %n,                      heptadecagonalNum(n))                                                # This code is contributed by ajit

## C#

 // C# program to find Nth   // heptadecagonal number  using System;  class GFG {             // Function to calculate       // heptadecagonal number      static long heptadecagonalNum(long n)      {          return ((15 * n * n) -                     13 * n) / 2;      }             // Driver Code      public static void Main ()      {          long n = 3;          Console.Write( n + "th Heptadecagonal"                                 + " number : ");          Console.WriteLine( heptadecagonalNum(n));                     n = 8;          Console.Write( n + "th Heptadecagonal"                                 + " number : ");          Console.WriteLine( heptadecagonalNum(n));      }  }     // This code is contributed by anuj_67.

## PHP

 

Output

3th Heptadecagonal number : 48


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