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Heptadecagonal number
  • Last Updated : 05 May, 2021

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

Examples: 

Input : 5 
Output :155
Input :9 
Output :549 

Heptadecagonal number

Formula to calculate nth heptadecagonal number: 
 



\begin{math}  Hp_{n}=(15n^2-13n)/2 \end{math}

 

C++




// C++ program to find Nth
// heptadecagonal number
#include <iostream>
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




<?php
// PHP program to find Nth
// heptadecagonal number
 
// Function to calculate heptadecagonal
// number
function heptadecagonalNum( $n)
{
    return ((15 * $n * $n) -
               13 * $n) / 2;
}
 
    // Driver Code
    $n = 3;
    echo $n , "th Heptadecagonal number : ";
    echo heptadecagonalNum($n);
    echo "\n";
    $n = 8;
    echo $n , "th Heptadecagonal number : ";
    echo heptadecagonalNum($n);
 
// This code is contributed by anuj_67.
?>

Javascript




<script>
    // Javascript program to find Nth heptadecagonal number
     
    // Function to calculate
    // heptadecagonal number
    function heptadecagonalNum(n)
    {
        return ((15 * n * n) - 13 * n) / 2;
    }
     
    let n = 3;
    document.write( n + "th Heptadecagonal" + " number : ");
    document.write( heptadecagonalNum(n) + "</br>");
 
    n = 8;
    document.write( n + "th Heptadecagonal" + " number : ");
    document.write( heptadecagonalNum(n));
     
</script>

Output 
 

3th Heptadecagonal number : 48
8th Heptadecagonal number : 428

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