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

Formula to calculate nth heptadecagonal number:

## 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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