Icosidigonal number

Given a number n, the task is to find the nth Icosidigonal number (Isdn).
The polygon has the many gons, depends on their gonal number series. In mathematics, there is a number of gonal numbers and the icosidigonal number is one of them and these numbers have 22 -sided polygon (icosidigon). An icosidigonal number belong to the class of figurative number. They have one common dots points and other dots pattern is arranged in an n-th nested icosidigon pattern.

Examples :

Input : 2
Output :22

Input :6
Output :306 Formula for nth Icosidigonal number: C++

 // C++ program to find nth Icosidigonal // number #include using namespace std;    // Function to calculate Icosidigonal number int icosidigonal_num(long int n) {     // Formula for finding     // nth Icosidigonal number     return (20 * n * n - 18 * n) / 2; }    // Driver function int main() {     long int n = 4;     cout << n << "th Icosidigonal number :" << icosidigonal_num(n);     cout << endl;     n = 8;     cout << n << "th Icosidigonal number:" << icosidigonal_num(n);     return 0; }

Java

 // Java program to find nth  // Icosidigonal number  import java.io.*;    class GFG  {            // Function to calculate      // Icosidigonal number     static int icosidigonal_num(int n)      {                // Formula for finding     // nth Icosidigonal number            return (20 * n * n - 18 * n) / 2;     }    // Driver Code public static void main (String[] args)  {        int n = 4;     System.out.print (n + "th Icosidigonal number :");     System.out.println (icosidigonal_num(n));        n = 8;     System.out.print (n + "th Icosidigonal number :");     System.out.println (icosidigonal_num(n)); } }    // This code is contributed by ajit

Python 3

 # python 3 program to find  # nth Icosidigonal number    # Function to calculate # Icosidigonal number def icosidigonal_num(n) :            # Formula for finding     # nth Icosidigonal number     return (20 * n * n -              18 * n) // 2    # Driver Code if __name__ == '__main__' :                n = 4     print(n,"th Icosidigonal " +                     "number : ",              icosidigonal_num(n))     n = 8     print(n,"th Icosidigonal " +                     "number : ",              icosidigonal_num(n))        # This code is contributed m_kit

C#

 // C# program to find nth  // Icosidigonal number  using System;    class GFG {            // Function to calculate      // Icosidigonal number     static int icosidigonal_num(int n)      {                // Formula for finding     // nth Icosidigonal number     return (20 * n * n -              18 * n) / 2;     }    // Driver Code static public void Main () { int n = 4; Console.Write(n + "th Icosidigonal " +                           "number :"); Console.WriteLine(icosidigonal_num(n));    n = 8; Console.Write (n + "th Icosidigonal "+                           "number :"); Console.WriteLine(icosidigonal_num(n)); } }    // This code is contributed by ajit

PHP



Output :

4th Icosidigonal number :124
8th Icosidigonal number:568

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Improved By : jit_t