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• Last Updated : 20 Jul, 2021

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 numbers. 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 arranged 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 numberint nthEnneadecagonal(long int n){    // Formula for finding    // nth Enneadecagonal number    return (17 * n * n - 15 * n) / 2;} // Drivers codeint main(){    long int n = 6;    cout << n << "th Enneadecagonal number :" << nthEnneadecagonal(n);    return 0;}

## Java

 // Java program to find// nth Enneadecagonal numberimport 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 Codeif __name__ == '__main__' :             n = 6    print(n,"th Enneadecagonal number :"                , nthEnneadecagonal(n)) # This code is contributed  by Ajit

## C#

 // C# program to find// nth Enneadecagonal numberusing 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

 

## Javascript

 

Output:

6th Enneadecagonal number :261

Time Complexity: O(1)
Auxiliary Space: O(1)

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